How do you check pulley alignment?
 

I am tired of being cautious when i want to romp on the pedal. When i let off too quickly in WOT my belt jumps off. If i gradually let off i dont have that problem.

When did it first happen, what was the last thing you did to the stang?

It happened first when i discovered my power steering pump was leaking. I replaced the pump and i havent had a problem until now.

The last thing done to the car was blower cams and a custom tune.

Also do you think this pulley will help me?

If if was working fine for several weeks, could be tensionor pulley going bad,its the one you pull back to remove belt. Easy way to see is have someone rev the engine and look in hood. See if the belt is slapping loosely through out the path of the belt. Did you replace the belt? How many miles on it, mine broke at about 50k. Also eye ball the path of the belt and see if you see it rubbing against any of the sides of the pulleys. You might want to check how the belt was routed to make sure it was done the right way, you never know maybe the new guy at the shop put on the belt.

I replaced the tensioner last year.... Replaced the belt Saturday. Now i carry all of the tools i need to replace the belt in my trunk.

How long have you had this problem?

I replaced the power steering pump and the tensioner last year because fluid was dripping on the belts. I dont see what can be making it jump like that now.

Someone else said that will happen when you let off the pedal at wot.