91 Olds Ciera engine performance problems

I have a 1991 Oldsmobile Cutlass Ciera with 235,000 miles which last summer started to lose power going up hills and then stalled when I pulled into a parking spot. After sitting 20-30 minutes car restarted and drove fine. At the time a mechanic recommended tune up and replace fuel filter. Because money was tight, I could only replace the fuel filter, which actually improved driving performance. But a few months later, when I started the car the idle was very rough, at 35-40mph the car felt like it was driving over those street cut outs, acceleration capability dropped…got a tune up but it hardly fixed the problem. Mechanic thought the ignition module was bad, but a new one didn’t cure the rough idle. Fuel pressure was normal and the injectors seem to be working fine. Since the tune up, there’s strong gas smell outside the car (lessens after engine runs a while), gas consumption has dramatically increased, and the engine shuts off repeatedly when slowing to turn into a parking spot or turning car around in the street. This winter cold killed my battery so the first thing I need is a new battery, after that then what? Should I get a compression test? What could be causing these engine performance problems?

Remove vac line from fuel pressure regulator. If fou see/ smell fuel in that line, then the regulator is bad and needs replaced.

My wild guess . . .

Leaking injector(s) or a bad fuel pressure regulator

What was involved in the “tune-up”? Were the spark plugs changed and the ignition system checked out?

Thank you for the responses. The tune up involved changing the spark plugs and wires. The only ignition system-related check out was to see if the ignition module was bad, but a new one didn’t solve the rough idle. I have to get the car to a mechanic this week so I’ll mention the vac line & fuel pressure regulator–thanks for that suggestion!