2002 Pontiac Grand Am SE wont start

I have a 2002 Grand Am SE V6 with 87000 miles. I have never had any problems with it until the last few months. Sometimes it just randomly won't start. I had it towed 2 times and it started once it got to the mechanic. He looked it over and could not find anything wrong. The third time I had it towed and replaced the following: spark plugs, fuel pump, fixed a computer problem, crank sensor, cam sensor, EGR valve, and replaced the coolant container because the old one would not open. It worked fine for about a month and then the service engine light came on. I took it to two different people and they could not find anything wrong. The last time I had it checked on Saturday. It is now Tuesday and it won't start again. I have been the only owner and have made sure that all regular maintenance and tuneups have been performed. I am at a loss, what else could it be before I get ripped off anymore?