Haven't posted in a while, but I have a 1994 Dodge 1500, 5.2 with 166,000 miles. All of a sudden, today when driving on the highway I noticed my rpm/engine dropping around 500 rpms, then back up 500 and kept going up and down while my foot was steadily on the pedal. Once I exited the highway, it seemed like it wanted to die will the RPMs dropping then only going back up because I hit the gas, whenever I hit the gas it goes back to normal but once I let go of the gas it hobbles back down to almost dying. I pulled over and the idle went SUPER low to about 500 RPMs, then the oil light came on, and randomly it popped back up to normal idle RPM and the light went off (it was only on for a few seconds).

Any idea?


UPDATE: I drove it around the block and it had ZERO issues, don't really trust taking it on the highway again though.

 

Tps, low/fluctuating fuel pressure i would check out first. Any codes?

 

No codes. Figured with 166,000 miles I will swap the TPS tonight and the fuel filter/pump out tomorrow and hope that cures it.

 

Just changed the TPS, still dropping RPMs at higher speeds (30ish and up). Sometimes it nearly dies when keeping my foot steadily at the same spot until I slam all the way down to rev it up.

 

Check fuel pressure while driving. I begin to wonder if the pump just can't keep up with volume required.

 

Replaced the TPS, brake light sensor, and Fuel pump with no avail.. Does this sound like possible clogged cat?

Codes just popped up:
37=Torque converter clutch solenoid CKT or park/neutral switch failure


21=02s sensor problem (oxygen sensor), upstream or down stream


Hmm now what

 

Now we have codes to go off of. I think your main problem is the lock up solenoid(#37). That would explain the rpm fluctuation(it's going in and out of lock up). The 02 code may be causing the driveability issue.

 

Remove the front O2 sensor from the cat. Go for a drive. See if anything is any better.