I have a 1995 Ford F350 Dually 460 EFI thats falling apart fast. I have a few more questions on my quest to make this truck run more like an 8 cylinder and less like a 4 cylinder with bad compression. So far I have ......Replaced the Alternator,
Replaced the Idler Pulley, Belts, Attempted a simple tune up snapping 2 plugs off in the head, drilling one of them out too big for the insert because I listened to a local auto parts guy instead of taking a pair of calipers and measuring the tap. and finally Replaced the fuel rail.

So.... I was driving this truck this past snow storm on the highway and all of a sudden it started running like crap and lacked even more power then usual. It now runs extremely rough and lacks power. I send the pedal to the floor and it smells super rich. I also have had the upper intake manifold off recently to replace the fuel rail. (pin hole at the fuel pressure regulator).

Could it be.... M.A.P sensor, Vacumm Leak or should I be looking somewhere else. Also where and what does the M.A.P sensor look like. and How do you find a vacumm leak on a efi system.

thanks once again

 

Since you smell unburned fuel, I'd look first at the ignition system. Try the easy stuff first... check to make sure one or more plug wires haven't come loose; pull plugs to see if any are fouled; check the timing; etc.

Also, I once purchased a brand new set of spark-plug wires of which two were bad. Strange things can happen.