My 92 gmc with a tbi 350 has a high idle problem. I have looked all over the web and cant find anyone with similar simptoms. It has an intermittent problem where it idles high in gear. It doesn't do it in park. The other day I found that if its idling in park just fine and I grab the shifter and move it almost all the way to reverse but not in reverse, it will idle high. I am trying to figure out what role the column switch plays in all this.*

Thanks
Lynn

 

I'd check the neutral safety switch, the ecm monitors it to see if its in park,drive, ect. See if its adjustable, maybe its loose.

 

I think the switch is working as intended. Its just idling wayyy to high while in gear. I was just holding it almost in gear to verify it was an input from the switch causing it to idle high. I don't know why it intermittently feels the need to idle high in gear

Lynn

 

Clean the IAC. May or may not help...