2004 5.4 FX4
 

I'm having issues with my truck some time shudders and dies randomly even while rpms are up. thought cats were bad so i removed the back 2, replaced plugs coil packs, and cleaned maf i dont know what else it could be my truck has 4x4 but wont lock in at all is there a vacuum line somewhere that would fix both issues or maybe just one, also i noticed by the passenger side engine bay by the pcm that theres a vacuum line that has a golf tee stuck in one end where does it lead to or suppose to go!!! please help or im forced to buy a dodge or chevy im having way to many issues with this thing and i absolutely love this truck and the package just want my 4x4 back with all its glory