Have a 1992 1.8 Turbo Diesel Sierra, it has good heater plugs, new battery and diesel filter. I’ve cleaned the tank and ran new diesel lines from the tank to the pump. I’ve swapped the filter head for a known good one.

Its hard started and when it does start it idles high and won’t rev at all. Anything I can do or try to get it back going right again? Also the Rev counter has stopped working. Thanks