2.3L ('83-'97) Slow acceleration; Little power; what else can I replace?

[JR307]

1993 2wd Manual 2.3L
248k miles; it had 109K when I got it
Over the last couple of years performance has diminished where going up grades or wind would force downshifting into 3rd and 45mph. Fuel economy tanked (15ish mpg) and oil consumption increased (~ qt/500-1000 miles) but none visible on the ground.
About a month ago performance further reduced to where i am not able to get up to 55 nor go up any grades without shifting down to 2nd or 1st and crawling.
I took it to my usual mechanic and he said engine compression was fine. I didn’t ask for particulars. He changed the Fuel filter, cleaned the MAF and advised the catalytic converter was bad and that I should replace it with a straight pipe. I ordered a direct fit replacement catalytic converter and installed it. Runs worse, so I start reading forums and start replacing parts, most of which are original.
List of parts replaced:
Catalytic converter
All 8 spark plugs (passenger side plugs very fouled and worn. Driver’s side worn but clean, no residue)
All 8 plug wires.
Both ignition coils
At this point I go for a drive, slight improvements, but check engine light still came on as well as acceleration and power issues remain.
New IAC
New PCV
New ECM
Problems persist, Check engine light still on.
New O2 Sensor upstream above new catalytic converter.
Since the new O2 sensor, idles fine and no check engine light after several different drives puttering around town. Power and acceleration issue still present. Feels like it wants to go, but just can’t quite. Like it is constipated (sorry for crude comparison).
What additional information would be helpful?
I am now considering that perhaps timing is off? Timing belt last changed at 181K (now at 248k).
Or EGR / DPFE issues? Is there another O2 sensor? Could it be the alternator?
Thank you for any input, the Dove and I appreciate it! We have coozed a lot of miles together. Now she is the crippled coozer
JR

 

[rusty ol ranger]

I would definatly get the timing looked at. I would also get a 2nd opinion in compression...unless you 100% trust your mechanic

 

[scotts90ranger]

Wouldn't hurt to do a timing belt, but not likely the issue. Normally when they skip a tooth they don't run.

The oil consumption tells of compression issues somewhere

Any strange noises? Ticky valves? It's rare but a bad lash adjuster or two could cause some bad running, but the compression would likely be wonky (to be technical). but you would also have worse looking spark plugs on some cylinders and not others.

Being EEC IV it's harder to diagnose than just plugging in a OBD II thingy and pulling up Torque on your phone to check things, but have you cleaned the MAF lately? It might be worth the $8 for a can of MAF cleaner, they can do odd things.

 

[Dirtman]

Stop replacing things and start testing things. Check fuel pressure, do a wet and dry compression test, check for codes (description for doing this on an obd1 computer is in the tech section) and finally do a full range of vacuum tests. Once those are done you will have a direction to go in. Until you do tests you might as well just start shuving $20 dollar bills in the intake...

 

[Fredness]

"Compression was fine" is a non-answer.
I'd start by verifying with warm, cold and wet compression checks.

Ditto on the no more spending, without hard compression numbers it's all guessing.

 

[scotts90ranger]

I third that, throwing parts at a problem has like a 15% success rate... +/- 8%, maybe 20%? I didn't look it up, we're all guilty sometimes but it is rarely the answer...

 

[JR307]

Thank you all for your input. I am sure many of you just shaking your heads and I understand why. I am just trying to do as much possible without spending more on a mechanic. And, yes, replacing parts is often not going to solve the issue and may exacerbate the issue by creating other, new problems. That said, I also reasoned that many of these parts are original, so replacing them seemed okay to me, logically.
I am shopping for a newer, more reliable vehicle which makes this less pressing to get fixed ASAP. But I want to have it around for puttering around town running errands, etc.
I don’t have the equipment to test, but I will see if a mechanic friend will help me troubleshoot it some more. (Not the mechanic that I pay to work on it.)
I fire it up every few days and it is rough idle for about 10-15 minutes and the check engine light is on. However, once it warms up, i can hear an audible difference in the idle and the check engine light goes off. I drive around 10-15 minutes and the check engine light doesn’t come on again.
Fuel consumption is high, nearly 8 gallons for 100 miles. Half what it used to do.
When driving, it takes a while to get up to speed in each gear. Tops out at 45-50 mph in 3rd. 4th gear won’t maintain 45+ mph. Any resistance from hill or wind is very noticeable.
The mechanic I paid to look at it replaced the fuel filter and cleaned the MAF and recommended I remove the catalytic converter and straight pipe it. The muffler shop wouldn’t replace a catalytic converter with a straight pipe. Because of this, I haven’t reached out to this mechanic again.
Thank you again for your input.

 

[franklin2]

How come you never read the codes? It's telling you it has a problem, I wonder what it is? A cheap code reader would tell you.

 

[scotts90ranger]

on a '93 you can read the codes with a piece of metal across the diagnostic pins, I've used anything from a small piece of street sweeper broom (the metal strips you find in parking lots and on the side of streets, it's spring steel and handy here and there) and have flattened a piece of solid copper wire with a hammer on two ends... the steel version can live under the hood with a magnet...

Anyway, you can find the code reading method HERE, use the picture for the analog volt meter method to put the jumper in then just sit in the seat and turn the key on with a piece of paper and a pen, count the flashes (should be 3 digit codes) then look up the codes.

 

[scotts90ranger]

That and blindly changing things just because they're original isn't the best option anymore, replacement parts aren't as high quality as they used to be, unless you get factory parts you have a 30-80% chance of getting a good part. There's a lot of garbage out there and too many parts that look and fit the same but have different specs...

 

[rusty ol ranger]

Or you can spend 30 bucks and buy an innova EEC IV reader. Thats what i did....makes pulling/reading codes a breeze.

I wonder if you got a bad coolant temp sensor? Codes would tell you that, normally.