sorry guys i did a search and too many things came up...read thru a few of them and still dunno which one could helped w/ my situation...

so this is what happens:

my friend has a 92 Civic Si here in Vancouver (CDN), and had just finished up a swap from B18C1 to B18C5 (basically just the long block, IM, IACV and TB)...yet we re-used the B16A (P28 i think) ECU that the car originally has, as well as re-used the fuel injectors and fuel rail (along w/ FPR)...

so when we started up the car...it runs fine; so we checked for leaks, there is none; checked for fuel pressure, and it was 28psi (so we adjusted it to 46psi w/ the vacuum hose off, so it's about 36psi when we have plugged it back); so we checked the timing, adjusted it; checked IACV and idle and was going to "calibrate" it for the right idle (unplugged it and try to adjust the idle screw to 550rpm w/ a digital timing light)...yet it says 380rpm so i almost have to back it up all the way out before it can get up to 550 to 580rpm....so i was like it seems like sth wrong, pluged the IACV back, reset CEL, start it up again and the car's idle is way too high and starts to rough, so i unplugged the IACV again and adjust it all the way back to 380 and with a little bit more i turned, it stalled....

so i sense sth is not right there...checked the car with a vacuum gauge and we got 20Hg at idle...sounds about right...

but whenever we slowly press on the throttle...the car revs up fine...as soon as we let go...it will drops down to 500 and pop back up to 900 or so...

yet IF we gas it like what we normally would do (not even floor it or anything)...the rpm will actually goes down before it starts its way up...and it will also goes down to 500 before it holds up at 900...

so we tried to check whatever is not right to us...and couldn't find anything...unplugged the FRP vacuum hose again (fuel pressure is up at 46 again)...and play w/ the throttle...then the engine seems more normal...

we dun even want to take chance to take the car out for test drive...can anyone help us?

here is the spec:

92 Civic Si w/ B18C5 engine, SiR ECU, SiR TB (bored to 67mm or sth), ITR IM, GSR fuel rail and injectors, some aftermarket adjustable fuel pressure regulator, new IACV, new clutch and flywheel...DC header and ITR catalytic convertor...ITR cat back...generic CAI...umm...what else will u guys need to know?

HELP!!!