1993 Aerostar. It has a rough idle and is hard starting after sitting for 15 minutes.

93 model 4.0L. It starts up and idles great when cold. Also starts and idles great when hot. If I stop somewhere for about 15-20 minutes or so it will sometimes take a few tries to get it to start. Always fires when you first turn it over. When it does start it will idle rough and/or hesitate for about 10-20 seconds. After that it runs perfect. There is no CEL, ever. Recently replaced MAF, cleaned throttle body, new O2 sensor, PCV valve, and temperature sensor. Autolite plugs have about 30k miles on them, . Today I stopped at McDonald's and it took about 10 tries to get it to start. Once it started it ran perfect after about 5 seconds. It was about 75F. Usually it isn't that bad though, it will start in 1 or 2 tries and takes a little longer to straighten out, but it is usually colder out since it's my winter vehicle. I am at a loss as to what it could be. I bought another temp sensor today at Advance but would like to hear some ideas before I throw $30 down the toilet by putting it in. I want to sell it but don't want to give someone that kind of surprise after they buy it. Thanks, Jeff.

See these two threads:

http://www.explorerforum.com/forums/showthread.php?t=398807

http://www.explorerforum.com/forums/showthread.php?p=3248660

Thanks for the response, had just about given up. I had read the first thread, not the second. I just ordered an oem temp sensor and am going to try that. Since it is an Aerostar I don't even want to think about the injectors. I can't even see them under the hood. Even though I'm a pessimist, I am leaning towards it being the temp sensor since I can't see how the injectors could only cause problems in such a tight timeframe. Most folks seem to have more problems when the vehicle is hot while I've never had that problem, along with never having a CEL on since replacing the O2 sensor. Also, when I couldn't start it the other day, I held it wide open like it was flooded and it didn't seem to make a difference. I know a lot of the aftermarket sensors are junk as I had similar problems with a Mitsubishi Eclipse once. One sensor it wouldn't run hot another one it wouldn't run cold. Fingers crossed.

Your thread was renamed, and moved into the Aerostar section. Check the vacuum lines, and the intake manifold gaskets.