Motorcycles, Snowmobiles, Go-Carts, ATV's and Golf Carts - 97 Yamaha Golf Cart GO FASTER/Not be retarded

So my electric golf cart is as speedy as a paraplegic and I want to make it faster. It's current max speed is about 11 mph when operating properly. However, now it has recently been acting weirdly. Previously, you could release all the pedals and the cart would zoom down a hill, gathering speed. Now, it seems it would have a governor on it because if you depress the gas all the way after it has exceeded its normal maximum velocity ,it will brake itself to try slow down to the 11 mph it normally goes. Also, if you keep the gas depressed when you first start down the hill it will NOT increase speed at all. Sounds like a governor, right? Only now, it's being more bizarre than usual. It seems no matter what I do, the golf cart will NOT speed up while going down any hill and seemingly actually slows down from the 11 mph max speed. Other similar problems include trying to slow down by just slightly pressing on the brakes, and the brakes for some reason respond as if you've jammed them all the way down, causing the cart to screech to a halt even if all you wanted to do was slow down to get the right timing on passing/avoiding obstacles or whatever it is. I assume the brakes/governor are responsible. Any advice on this problem? If you have any ideas for increasing the max speed as well (besides a lift and bigger tires) would also be a tremendous help. The brakes are rear brakes with little flexible but strong wires that resemble a bicycle's braking system that basically pulls the wires going to each tire that in turn applies the brakes. Just in case that's helpful.

How long have you had the cart?

Has the cart acted the same way since you bought it?

I've had the golf cart for about 4 years and no, it has not acted the same way since being purchased.

By the way, do you think extreme heat plus humidity living in the South could have any influence?

First, I would make sure your brake pedal can move freely and retract completely when you release the parking brake. The brake pedal assembly is pretty open underneath the cart so it can pick up a lot of dirt and desbris. The pedal should "snap" all the way up when you depress the throttle pedal.