I have a 84 300td that has a lot less power than our 84 300d.
The car has a boost gauge and I haven't been able to get it to go above 4 psi, I check boost on a 5% grade with foot to the floor car goes 55 mph.
Things I have done:

- changed filters
- cleaned tank and screen
- cleaned banjo bolt on intake and alda
- run line from banjo direct to alda
- disconnect overboost line and check if valve was working with air
- adjust valves
- check cam timing, it was good
- set injection pump timing , it was retarded 3 degrees
- checked injectors, good spray and pop pressure
- turbo spins freely no damaged fins or excessive play
- turned uo alda 1/2 turn, got more low end and more smoke

After all this car runs smoother but still no top end and 4 psi max boost.

any suggestions?