1994 Ford Mustang need help asap!

It sounds like you're trying to describe a misfire. Start with the basics, ... Spark plugs and wires. A failed ignition coil will cause two cylinders to misfire.

I need details. Did you replace the parts first, then the problem started, or did you replace parts to try to solve the problem? Rather than make me suggest a bunch of stuff you already did, why don't you include that information right away? What else have you done to diagnose this and what were the results?

If you saw a puff of black smoke from the tail pipe, that could suggest the misfire is due to a loss of spark or there's too much fuel going into the engine. To not overlook something simple, look for the fuel pressure regulator on the fuel rail on the engine. Pull the vacuum hose off it and check for raw fuel inside it. If that hose is wet, replace the regulator. If that hose is dry-rotted, replace the hose. Low vacuum to the regulator due to a vacuum leak will make it look like you're accelerating which calls for more fuel pressure.