We have a 91 T/C w/ 3.3L engine. The problem is below 30 degrees when starting the van in the morning, we get backfiring through the intake. It will start for a few seconds then pop through the intake as if timing is off. If you continue to try and start it it will fowl the plugs. We have already checked the air and coolant sensors, swaped out computer, ignition coil, map/baro sensor. Fuel pressure is correct. If outside temp is 40 degrees or up it starts and runs like a champ.