Are you still getting the MAF sensor code? If so, that is where I would start. Clean it, reset, retry. You mention an "intake gasket" was replaced. There are a few gaskets in the intake system, which one did he replace? I would suggest taking the 'big tube thing' apart and inspecting it for cracks. Clean the throttle body while you are at it. Replace the gaskets along the way (they are cheap). If you still get the MAF sensor code after that then maybe try a new sensor (can always return it if it does not fix it).
My truck ran much better after I built a DIY smoke machine to locate vacuum leaks (post with instructions in the 'Projects' section). Was not at the point of throwing codes but it was leaking like mad all through the intake/throttle body. Cleaned it up and replaced the seals and it no longer sucks in unmetered air.