1995 Ford Thunderbird car starting also idleing

I have a 95 ford thunderbird with a 1990 mustang 5.0 and sometimes the car will not start. This usually only happens if I start it up alot on the same day, or it will probably not start if I just turned the car off and then a few minutes later I try to start it again. This does not always happen though, only sometimes. But what I think is weird, is that if after the car doesnt start and I wait about an hour or so, then it will fire right up. It doesnt make sense. I thought it was possibly the starter, or crank sensor. But I do not know, can you help me?
also my car idles a little funny. Sometimes if I start it up in the morning for the first time, it will idle at 2500 rpm, then go down. But it always idles funny, it will go up and down, thenit will usually just stall out. Is it the idle sensor or something else? Thanks.