It's been a couple weeks since I had my cam installed. For the first 3 days afterwards, my car ran AWESOME. Then that Saturday, my transmission died. I then had a friend put another transmission in using my torque convertor. It was still messed up. Then he put in a different torque convertor with the new (had 80k miles on it) transmission and it seemed to work. However, it shifts really soft.

First off, would using my bad torque convertor in a new tranny hurt it?

Now to the real problem. It has only been since the transmission install that I've noticed my car running VERY strange at low rpms sometimes, usually between 1000-2500 rpms. It just seems like it struggles to make power, but it isn't misfiring as far as I can tell. If I give it more throttle while it is doing it, it will usually pull out of it. I'm not sure if it's something to do with the cam or transmission. It's like it almost feels as though the exhaust is clogged or something (which I doubt since it has headers/y-pipe/no cats/no EGR). An exhaust leak wouldn't cause something like this would it?