1992 Eagle Talon Engine stalling, Spedometer/Odometer not w

Right before I come to a complete stop, the engine quits, I can start it right back up and keep driving. This happens about 30% of the time when slowing down. The times it dosen't though the rpms sometimes drop to 500 or below, and the engine barely recovers. This problem occured within 10 minutes after the speedometer and odometer stopped working, all other gauges work. I also noticed that 1 of the 2 wires that connect to the negative terminal was disconnected. I hooked it back up, didn't fix anything, but could have this created one of the problems? (I disconnected the two wires when installing speakers, and I guess only connected one of them, and I drove with ony 1 of them for at least 100 miles before noticing)