I truly hate intermittent problems. Let's summarize:
I've got a '97 2.3L 2WD 5spd with about ~250k on the clock.
On my morning commute with outside temps in the mid 60s, all is well and usually no problems.
In the afternoon with outside temps in the upper 80s, it'll idle at about 800 rpm, then it seems to want to stall (rpms drop) then it surges to about 2000 and eventually settles back to about 800. it actually stalled on me a few times when stopped. It will also stall on me in traffic at highway speeds, or any speed for that matter.
While moving it feels like the engine stops firing for a moment and then kicks back in. Sometimes its just once, others it'll happen in rapid succession and it bucks. The truck runs beautifully in between incidents. I tried swapping the coil packs, which did not do anything. On a '97 2.3L, the ignition control module is integrated in the PCM.
A few times now, I've had the fuel pump relay click and chatter and the truck wouldn't start. When I jumped the relay, the truck would start, but still try to die.
When I finally rented the tester from AutoZone, I found that the fuel pressure sits around 40psi when running and goes up to about 45-50psi when it starts bucking. If it managed to hit 50 it stalled. After the test, I'm pretty sure the fuel pump is fine.
The only codes I was able to pull were P1443 & P0420, which have not come back since I installed a new Magnaflow cat, replaced the O2 sensors and replace the purge valve assembly this past week.
Possibly related: the speedometer has been flaky. Usually it sits at 0-20 mph while I'm cruising at highway speeds. If I let off the gas, the needle will rise. When accelerating, the needle drops to 0. Its been doing this for a few years. I've tried replacing the VSS, gauge cluster, etc... The only thing that seemed to help was cleaning up some of the grounds, but the problem would come back.
Anyway, I'm looking for help. I'm suspecting the PCM.
