Slow window.
 

If I don't touch my window for a while, the speed is normal and the window operates beautifully. But if I've operated it recently and try it again, it is really really slow and sounds like the motor is straining. Does this sound like the motor is going bad? I pulled out the regulator unit and cleaned and lubed it and this did not help. Is there any way to test this to make sure it's the motor?

sounds like you need a new car.:rofl:

Maybe I'll just rebuild and port the window motor.

Alternator going bad maybe?

I have no other signs of a battery/alternator issue, and my PFC reads around 14V at idle. The driver's side works normally also so that's not the issue.

Do you notice a drop in voltage when it acts up? If so see if there is high amp draw.

I have a similar problem, also only on my passenger side window. If i try to operate both windows at once both sides really struggle.

Have you tried cleaning the rails?

all my rx7s have always been poor with the window speed..i would suggest cleaning and lubing the rails. also if you have not done the ground wire mod do so at this time it might help.

I have already cleaned and lubes the rails, but it has not helped. Could you give some more info on the ground mod?

My 3rd gen (51k miles), a previously owned very low mileage 91 2nd gen vert, and a current low mileage 89 GXL all have slow windows.

They are just slow. They always sound like they are going to die, but get there eventually.
No alternator or battery problems with any of them.