So heres the story:

Driving around late one night and I pull up to a red light. Sitting there I'm thinking "Damn my exhaust sounds really loud." Pull into a parking lot and my exhaust is just hanging there in my engine bay. All 3 bolts that hooked up to the turbo are MIA (The threads are not stripped either). Luckily I was about 2 blocks from home so I took it real easy on her getting it home. Replaced the gasket, got new bolts and added lock washers to the combo.

Now the problem:

Upon firing up from a cold start, if I try to rev it the car will either die or slug down and drop to 100-200rpms. After the car warms up to operating temperature it runs fine. Pulled my codes and got code 42: MFI relay. Went out and checked my ASD and fuel pump relay. Only thing I found was on the relay closest to passenger side of the car (not sure if its the ASD or fuel pump, MTX tranny) one of the wires that fed into had fallen out of its butt connector. Re-connected the wire but to no avail. Anyone know where I should start looking or what to do?

Built bottom end
420a turbo
Megasquirt
Walboro fuel pump

If it's running differently cold vs warm, I'd double check to make sure your temp sensors (IAT/CLT) are still okay. Not sure how that plays with MS, but it's a possibility. If you've got MS controlling your fuel, I don't know how much influence the factory MFI relay has on things.

Replaced the ECT but nothing new.

I tested the IAT (warm) and got a value of 16k ohms. Specs say on a warm test it should be between 600 and 800 ohms. Going to let the car cool down and test it cold.

TPS was checked and solid.

Any other suggestions before I inspect the IAT further?