Want to replace the joysticks on the 2nd gen controller and possibly the built in mic as it is crap and unusable also...

Check coolant system, such as the thermostat mentioned above. The thermostat wouldn't cause high rpms directly but it will cause high internal temperatures and high engine temps can cause the motor to work extra hard to perform the way it supposed to. Check for proper compression. Check each cylinder for proper compression. Check for leaks in the air intake, air filter housing, vacuum lines, and exhaust. Check the timing. Belt/chain, spark plug gaps, distributor if you have one, possibly the trucks computer. I've seen cars run poorly just because the computer hadn't been reset after a battery change. The computer was stopping the ignition sequence because it thought the battery was still bad. Reset the code and the car started up. Get a second, third, fourth opinion. Go to a Dodge certified mechanic. Pick a shop that deals with these trucks all the time. They'll know these engines and it's systems better then they know their wives. Good luck.