Having a slight problem, new to mustangs and just got a 93 foxbody (5 speed) a few days ago. It Sat for a while, not sure how long. Anyway, it runs really rough. During idle it isn’t too terrible, sometimes it might vibrate. But the real problem is when I try to drive it. The car has no power whatsoever, it is really hard to accelerate. I don’t have a tac but I’d say it doesn’t go over 4K, no matter what gear I’m in. For example if I’m going 55mph I can’t shift into 4th because the Rpms drop too much and it shudders. If I run it long enough sometimes it’ll just jolt like it lost fuel delivery, and other times it’ll just straight up stall. I did the usual tune-up yesterday (air filter, spark plugs, fuel filter, oil change) I took it for a drive still no difference, after about 10 minutes of driving it just ended up backfiring and stalling out. So after I got it started i took it home, shut it off and let it sit for about 10 minutes. Started back up and it idled fine, so I took it for a drive. It actually had power! I could go through all the gears with no issue at all. Drove fantastic, I actually noticed the tachometer started to work as well. I was driving around for maybe no more than 15-20 minutes and the tachometer stopped working and back to the same issues. It stalled at one point and I was on the side of the road for about 8 minutes trying to start it had to rev the out of the throttle to get it home. I’m at a complete loss, I’m thinking fuel/air. Maybe even electrical. I just need some suggestions of possible causes so I can at least start trying things. I have no idea where to go from here.