Accent starts sometimes, and wont turnover others???

My girlfriend has a 2000 hyundai accent. For the past 2 months, we have had problems where it will run just fine for awhile, then one day she will get in it, and it will turn over, but not crank. One time, she got in it to go to the grocery store, cranked up, she shopped for a few and when she went to get back in, it wouldnt crank. It sat there for about 30-45 minutes, she tried it again, and then it cranked. The same thing happened to us another time about 2 weeks later. We took it to a mechanic and he thought it was bad coils because when he would put heat on them, it would crank. He replaced the coils. It ran fine for exactly 2 more weeks and then it happened again. She waited for a little while and then it cranked back up. The spark plugs are new, new coils, pretty new altenator, pretty new battery. We then took it to another mechanic to run a diagnostics test to see if it would give us any codes back, and it didnt. But, at the time, it was cranking. We can never get it to a mechanic when its not cranking, because usually, it will crank back up after a half hour or so. She had her MAF changed out a couple years ago because it was acting goofy, but a code did pop up then,and the check engine light was on. Now, it runs fine when cranked, no codes, and no check engine light. This morning it did the same thing, wouldnt crank. Its colder than hell outside (about 30 F), and it seems to do it when its really cold, but what doesnt make sense is when it cranks at the house and then she drives it to town, cuts it off for a few, and then it wont crank, I dont understand that. I dont know what the hell to do with it. If anyone has any suggestions, they would be very appreciated.

My girlfriend has a 2000 hyundai accent. For the past 2 months, we have had problems where it will run just fine for awhile, then one day she will get in it, and it will turn over, but not crank. One time, she got in it to go to the grocery store, cranked up, she shopped for a few and when she went to get back in, it wouldnt crank. It sat there for about 30-45 minutes, she tried it again, and then it cranked. The same thing happened to us another time about 2 weeks later. We took it to a mechanic and he thought it was bad coils because when he would put heat on them, it would crank. He replaced the coils. It ran fine for exactly 2 more weeks and then it happened again. She waited for a little while and then it cranked back up. The spark plugs are new, new coils, pretty new altenator, pretty new battery. We then took it to another mechanic to run a diagnostics test to see if it would give us any codes back, and it didnt. But, at the time, it was cranking. We can never get it to a mechanic when its not cranking, because usually, it will crank back up after a half hour or so. She had her MAF changed out a couple years ago because it was acting goofy, but a code did pop up then,and the check engine light was on. Now, it runs fine when cranked, no codes, and no check engine light. This morning it did the same thing, wouldnt crank. Its colder than hell outside (about 30 F), and it seems to do it when its really cold, but what doesnt make sense is when it cranks at the house and then she drives it to town, cuts it off for a few, and then it wont crank, I dont understand that. I dont know what the hell to do with it. If anyone has any suggestions, they would be very appreciated.

You say it will turn over but will not crank?:confused: I think you mean that it will turn over but will not start. When this happens check and see if you have spark, it could be your crank angle sensor starting to go.