Idle surging when decelerating.. ?

TheFleshRocket

Founding Member
Jul 10, 2002
208
0
16
Southern Ill Annoy
When I'm slowing down and put the clutch in (to put the tranny in neutral or downshift), the engine will sometimes drop to around 500rpm and then surge up to around 1400rpm. It will drop then surge a couple of times before settling back to the ~900rpm idle. If I blip the throttle lightly while it is surging, it will immediately settle back to the 900rpm idle.

As far as engine mods, I've got:
190lph fuel pump, 25# (I think) injectors, 40psi fuel pressure, F-cam, GT40 upper and lower intake, 1.7:1 rockers, GT40 heads, K&N open element

Any recommendations as to how I should try to troubleshoot this problem? Aside from the issue, the car drives great.