Rough idle at a stop

I just had my intake manifold gasket replaced and exhuast maifold and since then when my truck gets to a stop light or sign i feel the engine idling rough like it wants to cut off ..actually a shake that was not there before this.So i took it back and my mechanic wants to run a fuel injection cleaner thru since he said that the whole top of engine was turned ocer thinking that something got in ..the truck accerlerates and starts up great just idles rough now ...Does this sound right to anyone?hes doing it at no charge. So whats it gonna hurt?unless something else appears which im sure will soon ....trucks dont last forever but i thought my 350 5.7 engine would run longer then this without a hitch btw its a 95 silverado and just hit 60,000+ miles on it. I'm the 2nd owner and hope it didnt flip before i bought it that would suck..hahahaha..Thanks guys .....

could be the fuel pressure regulator, alot of times those spring a small leak and spray fuel in thru the vacuum hose, causing a rough idle condition. id say pull the vacuum hose off of the regulator and if fuel drips out of it, get a new regulator. if the regulator appears fine try carb cleaner through the throttle body and make sure to get the IAC valve on the top part inside of it, that could help too?

just my :2cents:
-nick
1999 silverado, 4.8, bone-stock

Thanks internic......i was reading about the IAC valve and was gonna try to install a new one but better to leave it to someone who knows what there doin but it helps to talk to you and others on here so when i do talk to my mechanic he wont think im a dumb chit ..hahaha...i appreciate the replys and help thanks alot Gonzo