Guys I need some help with my 2006 belta. I had an accident a while back in which my gearbox was destroyed (the car's body was intacy but it got hit from down below, pretty nasty accident) and I had to go for an engine replacement (I could not find the gearbox for the 1 KR-FE instead bought the whole engine - 2SZ-FE (1300cc)). After I had the engine replaced the CEL used to come on frequently but at random. Whenever I restarted the car it went away but would come back from time to time (on a similar pattern where I had to restart the car to make it go away often times 4-5 times) . The desi mechanics had absolutely no clue what was going on, the guy at nazir autos[ G-8/1 Islamabad ] was extremely rude to me (for no reason, I did not even say anything to him, he started to shout at me on the phone when I sent the car to him 
) . I took the car to sawat then and somewhere along the way the car started to heat up and shut off randomly. It was extremely hot and the car was overloaded (family just ignores me when I ask them not to do such stuff sigh) when climbing the cliffs. We cooled the car down and added water to the radiator. It then came back all the way and sped along the motorway just fine but then the same problem started to occur (car would die out randomly and display the engine overheat and the CEL) . I then gave the car to toyota and had them diagnose it - they came up with three error codes - Rough idling , Throttle relay motor high , engine stall and one other code related to the throttle circuit. Anyways, they gave me a costly solution and changed all my wiring. I have been driving the car for a week since then and there has been no problem and idling has also gone away but only recently this morning and at night today the CEL came on once again but went away with a restart. I have used original coolant in the car. I do not want to go through this diagnosis hell again and was hoping the seniors here could help me out. For now, I cant afford to buy a new car (constructing our house) and have to make do with this one. So far, people have been very rude to me (just because I tell them that I have changed the engine) while the Toyota guys I believe are just as lost as myself. I have concluded it maybe an engine misfire that may be causing this but I really do not know.
