1987 Lesabre - Rich fuel/rough start & idle

My parents left me their 1987 Buick Lesabre V6 3.8L MPFI with about ~110,000 miles on it to work on over the summer. They haven't taken much care on the car throughout its lifetime and so parts were hardly or not replaced at all.

It has an extremely rich fuel smell and sometimes I can get 'rotten eggs' smell if I ever get it started.
Starting the car on the other hand is another story, 90% of the time it refuses to start or will give a small hint with a silent puff*. When I get it started it seems to idle inconsistently and I get a rich fuel smell from the exhaust. I haven't tried driving it because it will stall within a minute after starting it.

The car drove somewhat fine before it had any work done on it last year. It only had the occasional jerks/deceleration in which my parents' mechanic pointed it out to be the unchanged fuel filter (of 20 years).
After awhile when the fuel filter was replaced, the sudden jerks/deceleration stopped but the engine stalled once a while. Thus my parents took the car to the mechanic again and he said it was the Distributor/Ignition Coils and had those replaced as well.
He also noted that the Catalytic Converter had a hole in it and replaced it as well. We never saw any smoke come from around there or the smell of fumes but my parents paid for the replacement anyways.
The car seemed to drive fine for a while afterwards but started to stall again and more to the point where the car refuses to start and idles extremely rough and had a lack of power.

I recently replaced the fuel injectors, spark plugs & wires(which were in terrible condition), and some rubber hoses which I believe were vacuum lines. The car still idles rough and stalls within a minute. I'm tempted to replace the fuel pressure regulator to see if that corrects my rich fuel mixture. As for starting problems I've heard that the crankshaft position sensor could be the cause, but I haven't a clue on where that exactly could be.