timing tensioner!!!!

on my 92 stealth DOHC i checked my timing belt today just to check on it and it was loose! just a couple of months ago i checked it and it was loose so i switched the tensioner (used one). so today after i noticed it was loose i figured i had to start it to get it to the drivewayto jack it up and get the wheel off and start the process of changing it and i noticed while it was running it wasnt looking very loose. so i got a screwdriver and gentley pushed on the belt with the handle and it seemed ok. so i reved it up to about 5000 and shut it off and it seemed perftect. is the tensioner bad or does it automatically tighten the belt as the engine revs up the tensioner is 100 bucks and ive stuck so much money into this car i cant hardley beleive it. so if anybody knows if my theory is right let me know so i can save some money.it must have been like this a long time cause i just checked it today and its been running fine other that the computer is bad but that should come this week. (
timing still on)