Having problems with '87 Ford Mustang Convertible lx 2.3 4 cylinder

I'm having some hopefully non major fixable problems out of my 1987 Ford Mustang Convertible lx with a 2.3 4 cylinder engine. Guess I'll start with alittle info on her, she was purchased by my grandfather for my grandma in the early 90's. She was only driven on the weekends, maybe sometimes during the week when us kids begged to ride in her with the top down. They took the upmost care of her. When they moved they parked her in their garage where she sat for 14 1/2 years until I convinced my grandma to let me go on ahead and have her last year. When I got her she had 14,000 original miles showing.. I knew she wouldn't be driveable right off and would need a few things, plugs, wires, oil change, filters, gas tank dropped and cleaned out, etc etc I had her towed to my home and began the process of getting her back on the road. Well after getting things mentioned above taken care of I got to hear her crank up and run for the first time in close to 15 years.. Not gonna lie i was quite disappointed that it wasn't that same smoothness i'd remembered but rather kinda rough and drove kinda rough BUT after a few days and some more tinkering she came back to life and was driving fantastic and my children got their first top down ride and loved it.. After maybe 3/4 months she started acting funny, running plain awful till one day i got tired of trying to figure out what was wrong and I myself parked her. she had been sitting for close to a year when about two weeks ago I realized it wasn't fair that I have this awesome ride just sitting up withering away so decided to revive her once more and get her back on the road. well she would turn over but would Not crank up, figured she jumped time. I bought a timing belt and prepared myself for possibly buying a tensioner and possible water pump. Had her pulled to where a dear friend of mine works and began taking everything off to check the timing and turns out the timing was fine on the belt. i believe it was a tad off at distributer Not quite sure how but she wound up cranking up but sounding rough, sounded like she was missing kinda sputtering, could smell a slight gas/exhaust from the rear, she would run at idle forever but as soon as I put her reverse she went dead, crank right back up no problem but in reverse kept going dead. I drove her back to my house and boy that wasn't fun or even a good idea. when i put her in drive she didn't ever go dead but when i pushed the gas she said no ma'am where you tryin to get to so fast lol Well in my fool head driving her home was my only option. I was excited that she was actually running. i got on that interstate and wished i wouldn't have. She had absolutely no power no compression and with the pedal to the floor wouldn't go over maybe 10 to 15 mph. thought I was gonna surely get ran over going that low speed in 60/70 mph traffic.. I finally got her home. other then putt putt'n to the nearest gas station once daily hoping she just needs to be driven, where I will put a little bit of premium gas in her and even some marvel mystery oil(did help but very little) as well hoping it helps. But she isn't getting any better nor worse.. As a single mom of 3 I would be forever grateful for any advice, suggestions, comments, questions, answers etc that would help me figure out whats wrong and bring her back to life again.. as of today she still hasn't even reached 23,000 original miles.. one thing that was suggested as the possible culprit is the valves.. and let me add I have not changed nor replaced anything except the battery since starting this operation car restore.. Not sure where to begin but we desperately need our ride back on the road, Having her just sit up and ruin is heart breaking as is watching my 1987 Chevy Camaro do the same.. Camaro been sitting almost two years. Any Suggestions big or small, on what to check please feel free to comment, I'm all ears ready to take in some valuable advice. btw sorry for this super long description wanted to make sure I didn't leave anything out.. Thank Yaw for Listening