Hello I have a 2002 dodge neon sxt, I just recently had the timing belt changed at about 104000 miles, the car was running good for a few days after, and then it started heating up to an abnormal temp, it will get to the third temperature bar, which is only normal if I'm driving through town, an having to stop at a bunch of traffic lights, but now it gets to that point on the open roads. The last time i was driving the car it felt like it was underpowered, it was also getting really bad gas mileage, and it felt like the automatic transmission was shifting funny, the check engine light was also on, and it gave me the engine code p0420. So what I'm asking is if anyone has had this problem before with there car? and what does the code p0420 mean? and is it possible that the mechanics screwed something up when they replaced my timing belt?