Rough in reverse?
When I put it in reverse sometimes, I think it happens when it's cold, the car shakes like the engine is missing, but it's fine when it's in any other shifter position. It doesn't need to be moving in reverse, just putting the shifter in that position does it.
I'm confused- shaking like that clearly looks like an ignition, timing, or mixture problem, but I can't figure out what about the transmission position could affect the engine like this.


