p0101 gmc serria 5.3

Trouble code p0101came in a couple of days ago. Truck wont idle and runs real rough. changed out the maf sensor still have the same code and the same engine problems no idle/rough running the only way to keep it running is throttle over 1200 rpms. I searched here and the most common problem noted with this code was aftermarket K&N filters. I am stock no mods of any kind.

Have you checked for power and ground from computer.Also make sure you have no leaks after the MAF sensor this will throw the reading off. What brand of MAF did you install, factory or aftermarket. Personally I have had bad luck with the reman aftermarket MAF sensors.

checked the conection and wires all looks good. All the other frezze frame data is about what you would expect. It just wont idle below 1200 rpm and missing badly. I guess I will change out the fuel filter verify fuel pressure and check the intake manifold for leaks next. Other than that I dont know. The maf was a reman. I did not like the way it looked when I got it. you could tell it had been rebuilt. so I sent it back and got a new one. but it made no diference.

Yeah with the high idle I would check for vaccum leaks around intake, pcv valve, throttle body, anywhere there could be a vaccum leak after the MAF setting the code. Might also try cleaning the throttle body because there bad to carbon up and the throttle plates hang open. Keep us posted.

Changed the intake manifold gaskets today and that cleared out the p0101 trouble code I had and the truck will idle somewhat now but sounds like it has a miss I now have a p0300 code in rechecked the intake for vac. leaks with a can of starting fluid no leaks found. new plugs and all 8 coils are firing. not sure what else to check any sugestions?

what's the fuel pressure?

Fuel pressure was 55psi.

that sounds a little low!

fuel specs call for 56-62. unpluged the vac. line on the fuel pressure regulator. fuel pressure increased to 68 psi and it made no diference in the way the engine was running. still missing and no idle below 1000 rpm.
Also tried pinching closed on the fuel return line. that also made no diference.