Ok 92 rs 305 tbi wake up go to car starts upbut idles bout 1500 rpms then goes down driving down the road things normal idles high like almost moves when foots on brake then 2 mins later back to normal so I replaced the idle air control looked over everything else came back fine 2 weeks no issues then today sittin at the light kind of a sucking sound high idle 1500 rpms so I pop the hood unplug the IAC 2500 rpms plug it back on shut car off starts up normal driving check eng light on high idle CHeck eng light off unplug I a c fixes it self I dont see anything else like vac leakes etc..how do I fix the erratic idle im new to the forum sorry if the section is wrong but I was thinking do I need a new computer its fine one day crazy the nxt help please

 

Remove the tbi unit, alot of times the gasket will go bad, it'll suck in at the narrowest point. This'll give you a chance to really clean up the whole tbi.