88 Bronco 2, low vacuum, runs rich.

I have a 1988 Bronco 2 4x4 2.9 v-6 95,xxx miles. Bottom end redone last year(rings, bearings, cam lifters and a valve job.), the motors runs really rough. Vacuum test showed 3 pounds. Pulled power brake booster line off with engine running and it didnt die. Feul pressure test shows 40 psi BUT falls to 0 after the high pressure pump stops running. No injectors are leaking. Any info or sugestions would be helpful. I pulled the upper and lower intakes off just to check gaskets, no leaks. But I did find a discoloring and bubbling effect between cylinders 2 & 3. These are the cylinders that wont fire or mis fire. Spark and fuel are there. Compression test showed 120 psi.

Check on the back side of the engine(I believe on the passenger side) for a ground wire. I believe it is the ground for the computer. It should go to one of the bellhousing bolts. I only know this after buying an 89 bronco 2. It would run very rich and had no power. I replaced all of the sensors and tried tons of things none of which worked. I only found it after the flexplate broke. I was reaching back to unbolt the bellhousing and found the wire. Someone had replaced the engine and forgot about the wire. I grounded it and it ran perfect after that. Hopefully it will help you