High Idle !!!

I am experiencing high idle with my 86 Chevy AstroVan. (It's a v6 4.3 liter) I have replaced the AIC, the O2, the MAP, the TPS, and as a last resort -- the computer. The only piece of the puzzle which seems to allow it to idle down what-so-ever is the "TPS" or Throttle position sensor, located in the center of the throttle body, passanger side, above the manifold. When removed, the engine idles down to where it should be, when in place the engine idles up. The only minor adjustment that seems to be able to be made to the TPS is to loosen it up and tilt it one way or the other (angle it slightly) but it just doesn't cut it. My brother who has owned several astros insists that I should go find a throttle body assembly in the junkyard and just replace the whole thing. A friend suggested spraying some type of carb cleaner in the area of the fuel injectors, but no such luck. It is a great running vehicle which has over 100,000 miles on it and only goes through a quart of oil maybe every 9,000 miles. I have changed the transmission in it to a rebuilt one that works beautifully. So I am pleased with the overall performance. However, with it idling so high I may not have this new transmission (automatic) for long before it goes and snaps a clutch disc or something because the idle is so high that is kicks into gear and squeals the tires. That can't be good. Please help!!! If I continue driving it like it is, the transmission will go again and it will be scrap in no time. :'(

Hey there! you are going to shake your head when I tell you whats wrong I have fixed this same problem many times! under the FI body (looked like an carborator) unbolt it and remove the alum spacer plate and PCV hose attached you will most likely find it completely plugged with carbon and white goo. clean the housing and the hose out well and replace components back ont intake manifold .Then install NEW pcv valve purchased at GM only! I found two seperate aftermarket manufatures of pcv valves have the wrong spring tention in them only a GM one will work properly! I took me a long time to figure it out the first time I hop this help you and all other Safari owner who most certainly have had the same issue!! CHEERS! RON Y

I had this problem with my 89 Astro. Check the gasket under the TBI. I think you'll find a big chunk missing which allows air to leak under the TBI.