98 5.9 - no mods

Sometimes after driving for a while, then putting the truck in park, the idle will be at ~1500, if I hit the gas to goose it, it will climb up to as much as 2000 and stay there. If I kill it, then restart, idle goes back to normal. I've been through 3 different IAC's as this has been a problem in the past and I know a few guys who have had some bad one out of the box, but no luck. I found a post from a while ago where a bad tps solve a problem much like this, just thought I'd post this to see if that sounds reasonable before I spend the money.

thanks

 

It very well could be the TPS. You can test it if you have a Haynes manual, or you can just replace it and have an extra for future troubleshooting if it is not the prob.

 

Check for vacume leaks too, keep in mind that the plenum gasket can cause vacume leaks if you haven't done that yet.

 

since turning it off and restarting fixes the problem, i'd lean away from vac leak to an electronic problem. and if it wasn't the IAC, then its probably the TPS. if you want to waste time testing it, you can use a digital voltage tester and probe the pins on the tps connector. you can measure voltage at normal idle vs fast idle to see if its changing. or, you can just replace the damn thing and move on... that's what i'd do.

 

replace=45$
2 minute test=free
hmm...

 

2 days post new tps and no problems so far