this is going to sound retarted but it could be ur battery. my instructor "which also has his own shop" had a honda accord come in and the problem was that sometimes the car would start and sometimes it wouldnt. it didnt matter if it was hot, cold, or anything like that, it just sometimes started and sometimes not. well it turns out that there was a weak cell in the battery. so a new battery was put in and the problem hasnt come back