92 k2500 idle surging

i have a 92 k2500 witha 350 tbi. i just got done putting new head gaskets on and started it up and it runs fine except when i put it in gear, forward or reverse, the idle will jump up and down and almost die. sometimes it will die. i have checked all the connections, plugs on the intake thinking that i me have not hooked something up but i do not get a check engine light at all.

:confused: what could it be

IAC. Should cost more than 30 bucks. Take off the Air cleaner, spray the IAC with WD-40, come back an hour or two, take it out, put the new one in, you should be golden.