93 SSEI... turns over, but wont start

I have a 93' Bonneville, SEEI.... A friend was suppose to clean out
the supercharger because it was loud... (I dont really know how all that
went), but I have had the car 4 yrs and never any major problems. 3
days after he was working on it, it started to die while I was driveing
it. ?????? It would not start again for a while untill it cooled down,
and then it would not stay stated for long. It did that for about 2-3
days and now it just turns over and doesnt start.
My friend did a diag. on it, and it said that the 23, MAT was low. We
checked and the sensor was not plugged back in. Can you tell me if that
might make the sensor go bad... or do you have any other ideas?
(I also overheard that my x may have did something to it--- if he did, what could he have done?)

could be a fuel pump... thats what happened when my pump went out.

Ty for your response.. It is getting fuel. So unless its maybe the fuel pressure or something, I dont think that is it.

Im having the dying issue with my car too...mines a 90.... could be a vaccuum leak which has been suggested mine is too.. if hes messin with hoses and what not in there he could have knocked one cockeyed...

When its turning over is it sputtering like it wants to start? and when you check the fuel pressure in the injector is is dribbling out or spraying out... ( should be spraying and not dripping)