I have a 01 se 3.1. The ses light wasn't on and i scanned the codes and got a p0128 or 6. It was coolant temp below thermostat level or something. I wrote it down and can't find it now. The mileage is really bad now just like that. I was driving to work today watching the fuel gage go down. I am thinking like 15 mpg. I used to get about 27 the last time i checked. I put a new air filter and plug wires on last week. It also surges in gear when you are up to speed and holding the throttle steady. Something like 5-750 rpms up and down. 1500-2250 area. I'm going to change t-stat but does anyone have any input to this. I just replaced the vent solenoid and gas cap to clear the p0446 code but now this.