Hello! I have what's probably a simple problem, but I need your expertise to really know what to do. Here's my issue: I've recently had the engine rebuilt because of a bad overheat. All original parts and the inexpensive labor here in southern Mexico. I am having a catalytic converter brought here in a few weeks because we couldn't find the right one here. So the mechanic here put in something else in the meantime. The code came up a few days later of P0420 catalyst system efficiency. Since then I've gotten two other codes, P0013 and P0014. I mention these jsut to give all the background possible, although they're not my chief question right now. A few days ago the car began to overheat. I had the AC on, but turning it off didn't change anything. I drove home, about a half hour, and as long as I was going quickly the temperature stayed normal, but as soon as I slowed down for a speed bump or went slower than 50 mph, the temp gauge rose quickly. I ended up turning it off about a half mile from my house, and getting it later after it cooled off. The water pump doesn't wiggle, and so I assume that it's okay. The coolant looks good as well, and appears to be half coolant, half water, although I can't tell for sure. It's bright green. Now the mystery to me is that since then I've driven it all around my little town, letting the heat go to nromal temperature, and with the AC on, and no overheating. I haven't dared to drive anywhere farther for fear of overheating. I almost wished it would overheat again so I could check to see if the fan was working, but it is working in town. Is this the thermostat beginning to fail? Or something else. I need to k now so I can order a new one from the States with someone who's coming here in two weeks. Thanks!