*Sigh* Studder/2k rev limit after idle...

[GT40MkI]

I've searched...

If this leads to a repost I apologise...
After being down with th 2.4 conversion for about a month, it was all completed about a week ago. (2.4 came from a running car with no known issues other than some lifter noise that is still apparent.) Car ran fine for about 15-20 miles of cruising last night. Tonight I rolled into the throttle to see how it felt and after a loud pop from the rear (exhaust?) the car resorted to barely running, I had to drive with "three feet" to keep it alive...

Symptoms:
*Car will rev fine if throttle is mashed as the starter is turned...
*Once the car has idled for a few second, you can go WOT and the car runs to 2k rpm like its hitting a msd style rev limiter..
*Idle is erradic and stumbles around 650-850rpm, going back and forth from turning off and barely running.
*Oil is fine( no water, fresh mobil 1 20-50, good pressure, none lost).
*Coolant is clean(no oil...)
*At idle, I only see 8-10" of vac instead of the usual 20ish..I know this could be caused by a number of things..

Coil pack?
CAS?
Anyone have experience with this?

Thanks in advance, tomorrow I'll do the usual-
Check plugs for fuel/oil and double check the gap..
Compression Check
Double check base timing
Check intercooler piping for leaks.

 

[turboholic]

-You took out the 4G63T and replace with a what motor? what's a 2.4? the one off a Mighty Max?

 

[GT40MkI]

Nah, its a 4g64, out of a mid 80s galant or 89-91(?) Hyundai...all the 4g63 pieces bolt right on...

I gotta go run some errands, I'll post up if I figure it out and its not tooo tooo stup[id of a problem

-Sean