Shaking - Engine? Cat? Something else?

[JimRummy]

Recently on a return trip from Santa Barbara CA (I live in LA) I was driving up a large grade, and had some very serious shaking, and loss of power.
Normally I hit this hill at about 75, and end up slowing to 65 by the time I reach the top. This was not possible due to traffic, and I was only able to hit it at the normal 65. At about the 3/4 mark of the hill I noticed that although my pedal was at a constant, my speed was slowly dropping (not too surprising for a 19 year old truck), now, by this time I was having to damn near floor it to keep it above 60, with people passing. By almost the top I had to floor it in an attempt to get her to downshift, but all that it wanted to do was buck violently.
When it did that I let off the gas, and it stopped, but when having to climb another hill (on the same trip home) it did it again. After the last hill it didn't happen again, on the whole way home, even on the large steep hill right before my house. After exiting the freeway everything felt fine, normal power, normal shifting, no codes thrown, or gauges doing anything out of the ordinary.
Its got about 106K on her, and damn near everything is original. I've talked to a few friends who've suggested some things, such as the fuel filter, fuel pump, and cat, but am on such a limited budget I don't have much funds to diagnose/fix. I've already replaced the fuel filter, the spark plugs are maybe 8k miles old, There's no water in oil, or anything like that. Although the truck seems happy, it still seems to loss power and chug/shake a little bit when on the freeway going up a hill. The last time it wasn't even steep, but long and drawn out. It seems to be around the 50 - 65 mph range, like maybe high 3rd, or low 4th.
Any Ideas?

Any thoughts would be much appreciated!

Also - I've heard about it being an Overdrive issue, so I gotta ask, whats the policy on driving on the freeway with the truck in Drive (AT)?

 

[sfwjesse]

I have the same year and engine truck with the same exact symptoms. I have new plugs, wires, fuel filter. Mine is a manual tranny. My theory so far is fuel pressure regulator or the coil pack. Ill let u know if i ever figure it out.

 

[modelageek]

Recently on a return trip from Santa Barbara CA (I live in LA) I was driving up a large grade, and had some very serious shaking, and loss of power.
Normally I hit this hill at about 75, and end up slowing to 65 by the time I reach the top. This was not possible due to traffic, and I was only able to hit it at the normal 65. At about the 3/4 mark of the hill I noticed that although my pedal was at a constant, my speed was slowly dropping (not too surprising for a 19 year old truck), now, by this time I was having to damn near floor it to keep it above 60, with people passing. By almost the top I had to floor it in an attempt to get her to downshift, but all that it wanted to do was buck violently.
When it did that I let off the gas, and it stopped, but when having to climb another hill (on the same trip home) it did it again. After the last hill it didn't happen again, on the whole way home, even on the large steep hill right before my house. After exiting the freeway everything felt fine, normal power, normal shifting, no codes thrown, or gauges doing anything out of the ordinary.
Its got about 106K on her, and damn near everything is original. I've talked to a few friends who've suggested some things, such as the fuel filter, fuel pump, and cat, but am on such a limited budget I don't have much funds to diagnose/fix. I've already replaced the fuel filter, the spark plugs are maybe 8k miles old, There's no water in oil, or anything like that. Although the truck seems happy, it still seems to loss power and chug/shake a little bit when on the freeway going up a hill. The last time it wasn't even steep, but long and drawn out. It seems to be around the 50 - 65 mph range, like maybe high 3rd, or low 4th.
Any Ideas?

Any thoughts would be much appreciated!

Also - I've heard about it being an Overdrive issue, so I gotta ask, whats the policy on driving on the freeway with the truck in Drive (AT)?

I have the same year and engine truck with the same exact symptoms. I have new plugs, wires, fuel filter. Mine is a manual tranny. My theory so far is fuel pressure regulator or the coil pack. Ill let u know if i ever figure it out.

-change the fuel filter if you have not done so

-I am not sure if you have a MAF or a MAP sensor. if you have a MAF clean it with a can of CRC. Check the airfilter and intake also

-make sure the CEL is on KOEO. Check for codes?

-you can pull the vacuum hose of the FPR and see if there is fuel in it.

-It is more likely to be a bad fuel pump. you can "borrow" the gauges from the auto stores and do a series of fuel pressure tests.

-it is a good idea to bring all the maintenance up anyways, check for bad vacuum hoses etc...