If Im not mistaken, what you are refferring to as the lift pump is just an inline electric fuel pump. Located in the same place as the inline fuel filters on the gasser trucks from the same time.

I had a 89 6.2 diesel for awhile, and what is happening to you sounds like the injector pump and or injectors.

I agree with bill on getting yout injectors checked out.

 

ok, so I just went out and hooked the jumpers to the pump wire and it started ticking. it was not doing this before, So I went and got another new ops and replaced the other new one and now lift pump is ticking when the truck is running. ok great, I drove it and it hasnt missed yet, but the check engine light came on and it lost a little power, I pulled over and turned it off and restarted it and the light was off and didnt come back on. This check engine light thing has happened before.

Now with this new ops, the idle oil pressure is down near the red, but when im driving is around 40 psi.