If you set the cruise with your foot of the gas here it the long answer from the Dodge Manual for my 02 Dakota.
If the vehicle operator repeatedly presses and releases the SET button with their foot off of the accelerator (referred to as a "lift foot set"), the vehicle may accelerate and exceed the desired set speed by up to 5 mph (8 km/h). It may also decelerate to less than the desired set speed, before finally achieving the desired set speed. The Speed Control System has an adaptive strategy that compensates for vehicle-to-vehicle variations in speed control cable lengths. When the speed control is set with the vehicle operators foot off of the accelerator pedal, the speed control thinks there is excessive speed control cable slack and adapts accordingly. If the "lift foot sets" are continually used, a speed control overshoot/undershoot condition will develop. To "unlearn" the overshoot/undershoot condition, the vehicle operator has to press and release the set button while maintaining the desired set speed using the accelerator pedal (not decelerating or accelerating), and then turning the cruise control switch to the OFF position (or press the CANCEL button if equipped) after waiting 10 seconds. This procedure must be performed approximately 10-15 times to completely unlearn the overshoot/undershoot condition.
size=2>...</FONT></DIV><FONT face=Arial size=2>> Every time I press switch on
cruise control (i.e., press Set button) the <BR>> truck would accelerate
5-10mph. Is this normal? It's annoying as hell, and <BR>> other vehicles I've
driven don't do this. Can this behaviour be changed?<BR>> <BR>> Dodge
Durango 99, 5.9L<BR>> <BR>> Peter <BR>> <BR>></FONT></BODY></HTML>