Low Voltage

[StacyAR]

I have a 1993 Grand Cherokee with an electrical problem. The Battery and alternator are both new and check out ok. Voltage at the battery and accessory plug both at 13 volts but the instrument panel voltmeter says 10 volts plus or minus and when you take your foot off of the gas it spikes down temporarily enough to cause a stall about 30 percent of the time. Meanwhile all voltages still read good everywhere else. It seems like where ever the drop is occuring also may affect the computer and it can't make the necessary adjustments in time to keep the engine running. I have checked all of the obvious connections and all seem to be ok. If it were a battery connection the voltage would drop at all points but at the accessory plug it never waivers. Ok I'm totally lost for an answer and I know I'm not the first person to have this Gremlin. I know there has got to be a "Hot Shot" out there that can point to the problem for me because I'm missing the target.