91 Olds hesitates and stalls constantly after fuel pump replaced

I have a 91 Oldsmobile Cutlass Ciera 6cyl 3.3 with 260,000 miles. Had no problems
with it during the first 5 months I had it. Drove it 100 miles round trip to work for about
a month until I got a place closer (4 miles). Anyways......fuel pump went out 3 months
ago and I had to have it replaced. Was having some hesitation and stalling but it would
always start right back up. I figured fuel cleaner would help so I added it when I filled
up. I drove out of town 60 miles and it broke down halfway home on the return trip.
Just lost all power while driving 70mph. Pulled over but could never get it started
again. Sat for a month before someone was able to finally pick it up for me. It started
right up but died halfway up the tow ramp. Anyways...figured out garage didn't change
fuel filter when they replaced fuel pump so I took it to another garage and had that
done. They diagnosed the car with a clogged fuel filter and vacuum leaks. I didn't have
this problem with stalling until the fuel pump was changed. Sometimes I can make it
20 miles before it just shuts down and won't start again until I try again the next
morning........sometimes I can't go 3 miles :(Any suggestions as to what to try next?
Would a vacuum leak cause this problem and if so since it didn't start until after the
pump was replaced....where should I start looking?