Im running a obd 1 p72 ecu in my 2000 gs-r due to my original obd 2 ecu starting to act kind of crazy. this obd 1 ecu is throwing a code 14 which is always listed as IACV/ECU issue. The car idles fine and runs great except it shifts harsh as if the rpm's drop too fast and it wont engage gears smoothly at all if i shift below 3.5k rpm's. I am also getting rpm surge between 1500-2000 no matter what condition, hot, cold, in gear, in neutral, all the time. I have tried everything i can think of to fix the issue which nothing seems to work. I checked the resistance in the IACV itself, checked the wiring, even replaced the obd 2 IACV with a obd 1 IACV but still the problem persists albeit not nearly as bad with the new IACV. I have read the inputs for the idle air control system all have a effect on the system so i have eliminated what i can that would cause the issue such as the brake and clutch switch, unplugged the power steering pressure sensor since i did a PS line loop since the pump failed, replaced the ECT. The only input that i know of that i havent checked is ELD but if it was malfunctioning it would manifest in other systems. Anyone have any ideas or is this ECU busted? I should note that most obd 1 p72's i see online go for $500+ and i thought it was too good to be true getting this one for $200. Also would hondata s300 allow me to tune out this possible ecu flaw or would it possibly persist? I am saving for s300 at the moment and have a p28 modified for vtec, boost by gear, and ready for hondata. If anyone has a resource that shows the internal circuitry to honda obd 1 ecu's so that i can check the caps, chips, and traces for that system then that would be amazing. I cannot seem to find any resources for internal diagrams on any honda ecu's besides guides on how to chip them.