The engine is a 5.0 that was rebuilt 45,000 miles ago. It now has 165,000 on it. Compression is 150 PSI, Vacuum is 19". I have plugged all vacuum lines except the MAP line for the test, and it does not change from 19". At Idle, there is a miss at times. It has lost its pickup. When turning on the AC, the temperature rises to well over half way on the gauge. The trans shifts hard, and is acting differently. Fuel mileage is about 10 MPG. I have noticed clicking sounds from the fuel injectors. Ford dealer said there are no codes, but something is wrong, compression was low and they wanted to put in a new engine, that is why I checked it. They had it for two days and that is all they would say about it. Any Ideas? Thank You, Ken

 

As far as running rough, try a fuel filter, air filter, and plugs wires and cap. After that if it still not good try a fuel injet cleaner at a good garage. Is is some thing that they run the truck on for like 20 min or so. Worked great for me.
As far the running hot with the ac on, prob need a new water pump and thermastat. plus clean the raditor, inside and out.
What is the compresion suposed to be? Are all the cylinders with in 10% of each other?
try that.

clipper

 

try having your fuel system cleaned with a motorvac system worked great for me,92 f-150 with 160k on it.

 

I have replaced the plugs, wires, dist cap & rotor, fuel, air and pvc filters. I had the garage clean the fuel system. I have come to the conclusion that it is in the emission controls on the right side of the engine. At times, the truck runs like a champ. Most other times it is sluggish. I now have a bubbling sound equal to engine rpm at times.