hi, i have a 1990 240sx coupe. it has a KA24DE with dc sports headers, injen intake and custom 2.5 inch exhaust. the problem i am having is that my car won't go pass 2500rpm. after some search i found many solutions, mainly a bad maf. here is the problem tho. the ecu gives out a bad maf code everytime, but the shop i took it to swap out two different mafs and it didn't do anything. sawp auto and manual ecus, didn't do anything. checked coolant temp sensor, o2 sensor, spark plugs, wires, rotor, cap. checked timing, checked injectors, fuel pump. nothing seems to be wrong but the car still won't go pass 2500rpm. super wired, so please any advise would be helpful thx.