94 Toyota Pickup, is mechanic being a doofus? Options

[hatazcat]

Hi, I have a 94 toyota truck 4 cylinder. 1.5 years ago I had a rebuild. things have been ok til recently. I brought it in for routine oil change and was told (this is the same place that did the rebuild) that i had an oil leak. i was kind of upset as i spent alot of money to rebuild the engine. however it was under a 2 year warrenty. so they took car of fixing it without charge. when i got it back it seemed fine...til a week later i went back to work and thus on the freeway....as soon as i got off the freeway it was running rough by the next day a blown head gasket. took it back to the shop they were going to fix agian no charge (they never gave me a reason for the blown head gasket...just said it wouldnt happen agian)....in the time it was at the shop the truck got broken into and the dash and ignition were ripped up pretty bad. Thus i had to wait quite awhile to get my car back with that going on. so i get it back and as SOON as i get off the freeway it dies...in fact when i take my foot off gas aft er being on freeway it dies....starts right back up tho. the mechanic says its the 'idle control valve' and wants 400$. i went in to do this and they forgot to order the part.....at this point i had had it and just left. went to another toyota mechanic and just by looking at it he said it wasnt the idle control valve...probably valves adjusted too tight. so now im totally confused what to do AND wondering if im damaging the car by driving it. does this sound like they f'd up? do valves get adjusted after an oil change? what else could cause the car to die after freeway driving? any help would be grateful.... heather