EZ-GO Cart 4M99 Loses power when driving, see my description

I have an E-Z-Go 1999 golf Cart and I am trying to track down an issue I am having. I made sure the batteries were fully charged. The cart takes off fine and it runs for about 60 feet then it loses power, does not sound like the solenoid kicks out. I back out of the pedal and wait for the solenoid to click then I tip back in and the solenoid clicks and the cart takes off again. I do this 2-3 times then the cart never gets back to the original speed and eventually it goes into a slow limp mode. I checked the main motor wires and the motor housing for overheating. I load tested each of the batteries and when I hook the up they show good but when I initiate the load test they move toward the weak range. I checked the voltage between the B- and the M- on the speed control module and it was at Battery voltage (36V). I then pushed the accelerator pedal and monitored the voltage at B- and M-, the more I pushed the lower the voltage dropped. I am wondering if there is a way to test the speed controller (Curtis PMC 73263 G01)? Does this sound like it could be a speed controller issue? Or something else? Any other trouble shooting ideas would be greatly appreciated.