2002 Durango R/T stalls at idle

Today I replaced the thermostat, housing, radiator hoses on my 5.9 engine. After reconnecting the battery, the speedometer flipped all the way to the right and when I started the engine it stalled. It startes and runs/drives just fine however, it will not idle. It stalls as soon as I let of the pedal. The only plugs I disconnected during the repairs were the Alternator and the A/C compressor. I re-checked and both are connected properly. Any ideas why it will not idle?
Thanks.