idle problems on 95 GSR...

Ok, i just got done swapping a B16 head onto my B18C1 block and now im having some idling problems. When i start the car, its very rough and it sounds like its gonna die. It also backfires pretty bad. It jumps from like 200-2000 RPM and of course its throwin check engine lights. Wierd thing is, all the lights on the dash stay on as if the car is on accessory and i dont know why. :uhoh: My check engine lights are 10 (IAT) which i know about and 21 (Variable Valve Timing & Valve Lift Solenoid). I know i might have a couple vacuum leaks but ive never had this happen and im stoked. Anyone have any ideas as to what some of my problems could be?

TIA,
Bryan

anyone? i need help!!

Thanks
Bryan