Extremely High Idle please help

[87s10]

Hello, before I get flamed I did try the search function first. Ok. I have a 1987 S10 with a 2.5 4cyl and a manual trans. When I start it, it immediately starts to idle higher than heck. It will not idle down at all. The previous owners put in a new trottle position sensor. No change. Also no check engine lights. Does the Idle Air Controller affect idle that much? I don't know what else to try. Any help or tips would be greatly appreciated. Thank you.

[gimme_a_350]

it certainly does. definitely worth checking into, although I'm not exactly an expert on the subject.

[Jimmiee]

Make sure the connections on the TPS are tight. I seem to remember there's a connector that has to be unplugged to set the timing. If this connector is left plugged in it causes a high idle. Not sure if this applies to your truck. Do a search here for repair manual and there's a link to the Ohio library where you can access the Mitchell repair information for your truck.

[cascott325]

check all your vaccume lines for breaks and dry rotting, do a tune up, plugs wires, cap and botton, etc. seafoam intake, break booster, gas tank.

[87s10]

Thanks everyone, I will give the seafoam a shot tonight and check all vaccum lines. I will post my progress. Thanks again.