[HoosierDaddy]

Well I think we've found the problem. I planned to do a follow-up when I actually had it running properly. I found an old mechanic who had the computer to hook up to the diagnostic port. He came to my shop and checked all the electronic side of the system. There were a couple inactive codes but nothing current. He then checked the fuel pressure and found it to be low.  At that point he diagnosed bad fuel pump and went back to the shop. I ordered a new pump. When he came back the next week after having time to think about it he tried hooking a short hose from the primary fuel filter inlet into a 5 gallon can of diesel. It ran great. At that point the fuel line was suspect. He looked at my old fuel filters that I had saved when this problem started and found them to be clean. He wanted to get it in his shop if the fuel line needed to be changed. The next week I rigged a garden hose down the side of the Newell from the primary filter inlet to the fuel tank and drove it to his shop.
When they took the fuel lines loose at the front they found black chunks of rubber in the inlet of the check valve. They appeared to be what is cut from inside the hose when the hose fittings were pressed on the hose end. Apparently after 26 years those chunks had broke loose and lodged there limiting the fuel flow. He thought I should get a new check valve so I spent a day running all over Northern Indiana going to bus company's and parts houses who thought they had the right one to no avail. I decided to disassemble and clean the check valve and it worked perfectly in my bench test ( I set it on end and filled it with fuel to assure the ball was sealing in the seat by observing leak down). The mechanic prefers to install a new one and for $70 I am not going to argue. So I'm waiting on a check valve from Newell to arrive next week. The inside of the fuel hose looks fine otherwise so we are not planning to change it at this time.