My dryer was not heating so I replaced the thermal fuse, and that was not it. Then I replaced the cycling thermastat and that was not it. Finally , I replace the heating element and that was it. The coils were red and the dryer was getting real hot. I closed the dryer door and there was a little spark but I checked it again and it was still getting hot. I put everything back together and put the dryer in place and now it is not working again.This is all in the same day within 30 min. What is wrong? Do you think the spark could have shorted out something?

That could have happened. Take a meter and check the fuses on the element and the other safeties. You need to learn to use a meter rather than guessing because you will never fix much the way you are doing it. Meters are very easy to use. You use it on "ohms" mode to check fuses and put it at the lowest setting unless it's automatic. Here is a booklet that shows how to use a meter: https://dl.dropbox.com/u/8010163/Whirlpool%204322537A%20How%20to%20use%20Test%20Equ ipment%20Service%20Manual.pdf
You always unplug the dryer and unplug one wire on the fuse or safety you are testing. On ohms you put one lead on each prong or each end of fuse after putting the leads together to test it. It should read the same thing you would read when putting both leads together. You probably installed the element where it could touch the side of the housing and you may not have thoroughly cleaned ALL air ducts like the one where the filter is located and the one going to exhaust. You have to get them all by removing them and washing them out. If they are dirty it will blow out the fuses and/or burn up the element by getting too hot. Make sure to vacuum out the motor, too. Here are the manuals: https://dl.dropbox.com/u/8010163/Whirlpool%20Dryers.zip