Hi everybody-

I've googled/searched the crap out of this issue, and can't find anything to diagnose the problem I'm having.

My 92 yota pickup will randomly "slam" you forward when you go to slow down by letting off the gas pedal, and will also hesitate and "slam" you backwards when speeding up again. It also idles rough every once in a while and just today after an oil change, it will not hold rpm while in neutral and pushing the gas. (Sitting still, I push the gas to rev it up to say, 1200 rpm, and it will rev up to that rpm for a few seconds then drop off, rev back up, drop off- all while I'm holding the gas pedal in the same spot.)


We had an extremely dry summer here in WA, and it was randomly occurring throughout the summer. We got a bit of rain for the first time back in august, and while the relative humidity was higher, the problem was gone.

The truck has a brand new throttle position sensor, new spark plug wires and plugs, new air filter, new pcv valve and some new vacuum lines.
There is no check engine light.

I'm at a loss as to what's going on. Any ideas?

 

Do you lube the Throttle body linkage at least every oil change ??


Bracket broke where it bolts to the firewall ??

Dirt or carpet causing the pedal to hang up.??

The cable itself is about to break and hangs up in the casing ??

 

Also - New Distributor Cap, Rotor and wires?

What condition were the spark plugs in? Any differences on the plugs between cylinders?

How's the fuel quality? Pull the injectors and test?

 

I would make sure the TPS is adjusted correctly. I'd also look for a vacuum leak. I have found that a smoke test is probably be the best way to find one.

 

No. I've only done basic maintenance on my vehicles. Never heard of lubing throttle body linkage.

Checked that- it's good.

Not an issue.

That could be happening, but how do I check that? Disconnect the cable and pull it out?


New wires, but it has an old cap and rotor.

They actually didn't look bad. I just replaced them because I wanted to try a regular "tune up" before other stuff.

Like I said before, I'm pretty elementary in my knowledge and abilities of working on vehicles.

This is a good possibility, considering this jerking problem started after I installed the new TPS.

Never heard of the smoke test. Don't a lot of people spray carb cleaner on the hoses to see if it revs up?