May be some problem w/ the climate control unit? It's a little bit difficult due to the design of the connector but try unplugging the ac compressor clutch wire to see if the hesitation goes away. The climate units are sort of expensive but they are on e-bay every now and then. Have you used the onboard diagnostics unit to check for any problem codes? The climate control temp sensors tend to get plugged up with dust and you can CAREFULLY clean them out with some canned air. They're located up behind the grab handles above each of the front doors.