Hi everyone new here just wanted to see if anyone has had this problem I have a 91 GMC sierra k1500 5.7 350 truck idle in gear 200 in park or neutral 500-600 idle usually is smooth although yesterday started to"lope" and has done that in the past but 85%of the time in gear it idles at 200 smooth in gear by the way all this happens when it is warm does idle higher when cold.some times will idle around 600 in gear arund 1000 in park wich seems normal but Ill pull in to a store or something then start it up and it will go back to 200rpm,dont know what to do because I would think if it was a vacume leak the idle problem would be consistent,same if it were a sensor mabey bad computer?any ideas are much appreciated,thanks!

 

Try changing the map sensor . It will have your symptoms.

 

Thanks I was thinking of that just didnt know that if the problem was that all over thw place if that would be the map but for the price ill try it.

 

Clean down your throttle body really good. See if that helps.

 

Just picked up some,thanks!