sick-punk

so you've probably heard this a thousand times but i cant seem to find what im looking for. ok i have a 86 gxl, i could hear ticking coming from my engine then my car started stutteringand lost power and now wont rev past 1500 to 2grand so i pulled over to check. Turns out one of my spark plug wires was disconnected i reconnected itand she still wont goes past 1500, so is the plug bad or is their something else that could cause this.