starting issue 88 supra automatic w/turbo help!

[ricerbaby]

i have an 1988 supra and it has had problems in the past. we put a jdm in it a few years ago and we had to replace the headgasket and other things. it will not start about 10% of the time. i will try to start it and it will turn over and over but will not start. i will turn it off and start it again and again, but it wont work. it will then start maybe a day later or a few hours, but it is always random. it was in the shop for two weeks and they could not find the problem. they checked all of the fuel lines and pumps, but as soon as they started to get close to the problem it would start up again and the problem wouldnt happen again for maybe a coupple of weeks. it is not the cam wires they were just replaced, and i dont know the problem please help! it is not over heating and not leaking except maybe a few unimporntant vacuum leaks. any ideas???