my car misses and backfires when floored, seems to run alright until floored thought it may be the opti but replaced it today and it still does it , i have also replaced the fuel pump, plugs and wires, fuel filter, could it be the injectors or the coolant temperature sensor? by the way its a auto.

 

I hate to say this, but you could have a cracked porcelain on one of the plugs. I've had this happen to me on my truck. Worth a shot and your not throwing anymore money at it. Although a pain. Try running it at night and have someone bring up the rpm's while you mist water over the ignition components.

Do you have an aftermarket ignition setup? The coil? Some of the cheesy parts stores ( Kragen, Autozone) will let you return parts without question. ( My friend did this after frying his MSD coil.)

 

stock ignition. i bought the car from one of my freinds and he said that it ran good till he let the car run out of gas and it hasnt ran rite since, ive done changed the plugs wires, fuel filter, fuel pump and opti, after installing the opti today the check engine light came on and i plugged it up to computer and it said the coolant temperature sensor was bad said the car was running 39 degrees that was after it had been running for 10 mins.

 

Possilbly running to rich and loading up? Did you change the sensor?