timing belt eater

I have a 98 contour right now that seems to want to eat the timing belt. I got it off of a guy because he couldn't make it run right. I took it apart (well front cover and valve cover, and found the timing belt to be really loose. I tightened the timing belt, replaced the plugs, and it ran like a top. Then it took about 30 miles or so before it ate the belt. I bought a new timing set, replaced it, and it started working toward the front cover and I think it's going to do it again. any ideas

Sorry to jump in on this thread but I seen your post "96 GC spark and wiring problems" did the computer fix it? I sent you a pm. could you let me know thanks. Charles

stupid question: are you using the correct belts? some have rounded teeth, others square teeth

idler pulleys or timing belt tensioner.

I have a 99 with a 2.0. I had to replace the timing belt and all the pulleys ( I had the one near the crank fail) I bought a kit for around 150 wholesale. I had to replace the timing belt again 10,000 later because I over tightened the tensioner.
I would check your pulleys to make sure the bearings are good. Also make sure your tensioner is not to tight. Hope this helps