Starter Problem

This is weird,

It seems like my starter works fine and turns over powerfully 1/2 the time, and the other times it seems like the starter can barely turn over, like its not getting any power for some reason (the car does start, but barely).

I can pretty much rule out that it's not a problem w/ the actual starter because this is a new stock remanufactured starter that I just replaced from Autozone.

I can also pretty much rule out that it is not a battery problem b/c I recently got the battery tested and it was fine.

I do have long tube headers but am not so sure the heat from the headers is causing the problem, b/c it seems like sometimes the starter turns over fine when the car is hot, and sometimes it does not turn over that well when the car is cold.

Any one have any ideas what the problem might be???

"Does it physically sound different? If no, then maybe the problem is actually the choke instead, if yes then perhaps some of the teeth are bad and you have difficulty when they line up a certain way. When you replaced it did you see metal shavings?"

I'm not sure if its the choke or not, but it seems if I press the throttle a little bit as the starter tries to turn over during the times it seems to be weak it definately helps. As far as metal shavings go, there were none and the flywheel teeth look fine.

"does it do it when the motor is hot ? Or does it matter ?"

It doesn't seem to matter, it occurs when the engine is hot or cold about 1/2 the time.