The way you can tell is drive the thing, and if you think it's weak, I mean WEAK, then it's probably shot. Get someone with a simular powered car to drive behind you as you floor it. Or you can always open the hood, find the linkage, rev the engine (you have to get it to like 5500 RPM because your car isn't moving) and watch it. The "arm" you can watch is located under where the throttle body sits.
Mazda 6S, V6, Speed Yellow
5 Speed, Sport package
Bose audio
Painted 'stash and HIDs!
w/Injen 1/4 14.750 @ 94.94
Former car:
99 Contour SE Sport Black MTX V6
SVT plastic...
1/4 - 15.012 @ 90.58