hard to explain

[akcamaro02]

about a month ago now, i had my tranny rebuilt and idk if the issue is the tranny but basically ever since then I have had a rough idle, you can physically see the RPMs fluctuate, it will idle about 650, then every 5 seconds or so will drop to about 550, then back up to 650, like it wants to die or something. that was the first issue.
now recently, including today, when you start the car up cold, you can feel like a baam or something, idk how to explain it but u can feel something move under the car, id say the tranny bc it feels like right under me but i can pinpoint it. weird thing is it only happens on a cold start. it's not super loud and doesn't seem to have a visible impact on the car thus far.
a friend mentioned maybe a bad tranny mount and when it starts cold the RPMs are higher and since the trannys not properly mounted it causes the tranny/engine(since connected) to move.

Any suggestions? I'm stumped. I know it can't be good bc its just one of those feelings it cant be good. it wasn't happening before the tranny rebuild

[cam98aro]

Re: hard to explain

i would replace the trans mount

[dmw319]

Re: hard to explain

+1 the trans mount is really simple to take out and inspect. if its bad throw on a new one and call it a day. maybe a motor mount also if that doesnt fix it.

[akcamaro02]

Re: hard to explain

today it seemed to be coming now more from the rear of the car.Something in the exhaust? Idk what in the rear could cause it