Obd1 b16 into my obd2 civic backdated to obd1 on usdm p30 ecu. The idle surges up and down for a while and will eventually settle at idle. I did the fingure test by blocking off the hole for the iac and it stops surging, so i took off the iac and cleaned it. This fixed the problem for a while but the problem came back. So then i got a known to be good iac from a friend and swapped them. This didn't fix the problem, i tried playing with the idle screw on the throttle body and it slowed the surging but has not gotten rid of it, i am getting ready to seal the passage off with some jb weld so please give me a solution. I CAN'T take the surging.