Hiccuping at 3000rpms

[RadioactiveSoda]

I bought a 1990 Ranger off a shady guy in a Ross parking lot and was misled (classic FB Marketplace). After fixing most of its issues, there’s still one that I can’t seem to figure out. When at 3000rpms, usually the freeway, the engine will start to hiccup and stutter as if it’s trying to shift like an automatic and is stuck between gears. This is it happening while driving
It doesn’t happen all the time and I can usually drive past it. I’ve been told I have an exhaust manifold leak if that helps.
anyone able to offer some advice?

 

[superj]

welcome!!

fuel pressure is good?

 

[RadioactiveSoda]

Not sure how to tell. I’m handy with a socket wrench and a YouTube video but not much outside that. I’ve replaced the fuel pump assembly since the gauge didn’t work.

 

[superj]

normally you have to hook a gage somewhere to check the pressure but since it runs good everywhere else, i would think its probably good.

we need someone who is a 2.9 person to come help. i wonder if there is possibly an egr issue? i have no idea what to check or where, i would have to google.

 

[superj]

maybe a crank or cam sensor is dirty?

we better wait till someone with experience comes on

 

[RadioactiveSoda]

Haven’t had any issue with startup or with it idling besides it getting quieter after about 5 minutes of it idling in place. My rear antilock light flicks on after about a few minutes of driving but I doubt that has anything to do with the issue.

 

[superj]

maybe you have a ground issue?

 

[superj]

you could test it by hooking jumper cables from the engine and transmission to the frame somewhere. test drive and see how it acts.

 

[JerrySab]

the 2.9l doesn't have a crank or cam sensor, that's handled by the distributor. In that vein, It could be a timing issue, could be pickup coil in distributor is corroded and not keeping up at the higher rpm, ditto points on the cap. Could extend to ignition coil, or wires attached. TFI could be giving up the ghost, but I believe they function poorly at all RPM when dying.

It reads to me as spark/timing issue. Before seeing the video I might have suspected the torque converter but I'm not sure you have an automatic anyway so nix that. Have you inspected distributor since you picked up the truck?

I'd also add, there is SO much wisdom on this forum. I'm fairly new and have a few years as an enthusiastic hack, but many of the voices are decades deep in ranger repair and are tremendously helpful.

 

[gaz]

I had 2 thoughts:
- ignition power
- fuel pressure