It'll start right up and hold idle for about 7-10 seconds then fumble below 500rpms and die. If I restart it and hold the rpms higher for maybe 20-40 seconds it'll still stumble a little when I let go, but it won't die. Then eventually it'll idle fine. Now I've only started it recently when it's sat for awhile (its away for winter) and its been cold. It was recently all apart for a new opti and waterpump. Is there any particular sensor that could be causing this? Also my air intake is a mess, I need an aftermarket one or a new stock one. If air pressure is affected by a leak in it, would it act this way? Only right after the filter box is it loose.

 

Bad Maf Sensor

 

Sounds like it could be a vaccum leak or an IAC problem. Mine did this once after I removed my intake elbow and put it back on; i'd left a gap at the bottom where the elbow slips over the throttle body. Once I put in on correctly the problem stopped.

Make sure all connections are secure betwen the maf and throttle body and that the vaccum line for the opti is connected good. I think Shoebox has a guide for cleaning the IAC valve if its not a vaccum leak.

 

EXACTLY what i was going to say...

 

Well the elbow did have a split in it right where it connects to the TB but I trimmed it clean and now its held on by a hose clamp, ghetto I know.
As for the IAC, I did clean it thoughly when I removed everything to do the headers and had to pull the heads to have a bolt extracted. Then I drove the car for awhile before having to rip it apart for the opti/waterpump ordeal. By the time I dicked around with that, I was done driving it for the year. So I'm not sure if the cold has anything to do with it or what. Could be a bad MAF but why does holding the throttle make it okay? After 20 seconds holding the throttle or reving it a little, it'll purr like normal. I'd lean towards IAC no?