So, i recently HAD anew transmission and clutch put in for me. I got the car back today to find that there is this weird RPM bog down issue. i idle at about 800RPMS, when i push the clutch in and put it into 1st it surges between 800 and 400/600-ish, i heard that it might have to do with the vacuum line but im not entirely sure, anyone have any input they can throw my way?

 

was the clutch bled properly? there possibly could be air in the line causing that surging, i'd have whoever put the tranny and clutch in to double check and make sure they bled the clutch properly.

 

Why would air in the clutch line cause surging?

I'd look at the IACV myself, probably time for a good cleaning. When you push the clutch in, it loads the crank and the IACV has to open up a little to compensate.

 

Coolant air pockets can cause this issue as well, the IACV and FITV both use coolant to operate, air pockets in these valves can cause them to behave weird.

 

My 94 prelude vtec has this same issue but when my clutch is applied my car stalls but it also bogs out
i have a fully built h22a1 with stage 4 clutch im in a bind an can't find reasoning for this issue