Have an 86 300SDL, OM63. Previously had a head replaced before it landed in my hands. Car made no boost at all, wold barely move when I got it. I replaced filters which were pretty bad, then checked injector timing. Injection pump was set to 13* BTDC via the A-B method. I check the valve timing, it is spot on. I pulled the pump and set it to 15* ATDC per the manual. Vehicle starts up much easier. When you drive it it will make boost now and drives decent with your foot in it. Shifts very hard though. The largest problem is that there is terrible throttle response and from a dead stop the car takes 10 seconds or so to get going. I did a diesel purge, no real change. No codes from the computer via a LED blink tester. I don't have a sweep meter but the LED tester has worked on later model cars that call for the sweep tool. As far as I can tell the computer only control idle speed and EGR in the engine anyway.

There is no catalyst or trap.

I need to know where I should look next for this performance problem. If I rev the engine up without a load it is slow to rev. There is something wrong here I just don't know what. Any help wold be appreciated.