Last summer i installed new exhaust from headers down to the tips, and did most of the mods in the "free" tbi mod help. I also replaced most of the sensors. Starting from the exhaust work my engine would occasionally miss while it was warming up and under load (moving from a standstill). It has been doing it more and more frequently until now, where I have to wait for it to warm up or else if I pull out in traffic it will cough a few times and almost die. I replaced the plugs and inspected the wires and it didn't fix the problem.

The engine also lags sometimes when you try to accelerate.

Anyone got any suggestions?

 

I dont think it has anything to do with your exhaust. Did you change you fuel pressure when you did the free TBI mods? Did you do any other mods that you are not mentioning? What is your timing set at?