Keep Getting CEL 43

well like it says, i have just swaped in a Z6 into my rex, i did the total swap, OBD1, and everything, i have been having no problems with the car, exept for this CEL 43 that pops up everynow and then, i know its the Fuel Sapply system code, but i dont knwo what to look for, i origanaly had a Y8 intake and i was throwing the code then, now i put the stock Z6 intake,(which has diff. injectors and fuel rail, TB,IACV,everything) and its still throwing the code.
OH and my fuel pressure is set at around 40-41 at idel and its about 50 with vaccume line off and blocked. plz help it seems like my fuel millage has gone to [email protected]#$ too.