1999 Trooper - Throttle Sticking

Hello

Although this is my first post to this forum, I've picked up a lot of information about my 1999 Trooper. I've only had the car for about a month and overall I'm very pleased with my purchase. When I purchased the Trooper it had 51k miles on it and had some trouble starting up. It also stalled out sometimes at idle. My first instinct told me to replace the fuel filter. The filter needed to be replaced but it didn't solve the problem. Ultimately I replaced the Fuel Pressure Regulator and that did it. It now starts up & stays running.

Now, my problem is this. Sometimes when I downshift or shift out of gear my RPMs are cranked up to 2-3k, sometimes more. This doesn't happen all the time, and sometimes happens during the first 5 minutes of driving, sometimes after an hour. Sometimes the RPMs are at 3k and I'm sitting still, then they slowly start to creep down to 750, but it takes a couple minutes to get there. I can also throw it in 4th & let off the clutch to bring them back to a normal level.

I had a couple of ideas but haven't been able to find anything yet. Maybe a TPS or the throttle cable (someone cleaned out the engine with a power washer & now some metal parts are corroded). It doesn't seem like my pedal is stuck b/c I pull out on it and it has no give. I was thinking maybe it was the spring that connects the throttle linkage to the throttle body, but wouldn't there be play in the pedal? If anybody could help me out or get me going in the right direction I'd really appreciate it.

Your throttle body plate (the butterfly in the throttle body) maybe full of carbon. you may want to spray it out with some carb cleaner.

also what you are discribing sounds like a classic case of a cracked intake manafold gasket.


see the FAQ's for more info.

Darn, I was hoping it wasn't the IMG but I guess its bound to fail at some point. It seems like a very common Isuzu problem. I'm just glad there is plenty of info on this forum to help with the replacement.

Thanks!

Another thing to check is the rubber boot at the end of the throttle cable, where it attaches to the throttle body. The boot can get soft & gooey with gas/oil/grease contamination & cause the throttle cable to stick. You can tear it right off if it's really bad & try to get another one (or just leave it), or just lube it up really good with a silicone grease or silicone spray. Keep petrolium based lubes away from rubber parts as it will soften them.
G/luck
Joel