Long cranking sometimes

My car listed above early build like January,1987. is in the repair shop for the umpteenth time for long cranking sometimes.
Because on an early build some sensors may be tied in with the cars "brain".
I had a problem in the past where a sensor was not in with the old-brain.
.
Rebuilt block 16,000 Miles on it.
New fuel pump and fuel filter.
injectors cleaned.
computer checked car okay.