My 2000 yamaha electric carts is slow in forward fast in reverse. Has new forward and reverse switch. Why would cart have almost no power up hill but will fly up hill in reverse?

It's possible that the motor, solenoid, or wiring has become disconnected or damaged. I recommend starting with a basic inspection of all the connections, wires, and components. If all looks alright, then you may need to have the motor and solenoid tested. If there is still no luck, then you may need to replace the EZGO golf cart motor or solenoid.

This sounds like a drive motor issue, have that checked.

This power plant can be tested with a scanner, the dealer would need to do it, but guessing is a more costly route, have it tested.

If this is a 5 solenoid cart then I would look at the forward/reverse switch. Sometimes one of the copper contacts will get hot and melt the plastic around it, causing it to sink in and not make contact. I have seen this happen where the cart will move one way and not the other. Other times the contact is so burned, it will not make contact either direction. If the contact is burned then the only cure is a new f/r switch.

Troubleshooting a golf cart - APLawrence.com

aplawrence.com > Miscellaneous

Mar 29, 2015 - If you need help with a golf cart, I suggest asking at Buggies Unlimited. .... Within a half hour I had everything in place, cinched down, connected and ready. ...it is still getting power to the forward and reverse other words itsworking and ... I let mybatteries completely drain and now the charger won't turn on, ...

Put Spring In Your Electric Golf Cart ' Golf Cart Talk Blog

https://www.golfcarcatalog.com/golf-cart.../put-spring-in-your-electric-g...

Mar 9, 2004 - On a car with 8-volt batteries, connect a 12-volt charger to each individual ... If you do not have a 'Regen' system, then just put the Forward/Reverse(F/R) switch into the .... speed controller stays dormant and will not permit the car tomove. ..... My other question would be did anything "fail" in the cart prior to ...

About Golf Cart Battery Chargers ' Golf Cart Talk Blog

www.golfcarcatalog.com/golf-cart-blog/about-golf-cart-battery-chargers/

Apr 1, 2012 - Tutorial on golf cart battery chargers, the basics, what goes wrong, ...BATTERIES ARE DEAD AND CHARGER WON'T COME ON ... This is usually indicated by a car that creeps when the brake is off and the car is in forward orreverse. ... a connected pair of batteries with a 12 volt, auto style battery charger.

Basic EZGO Golf Cart Problems And How To Fix

Right here:
http://www.vintagegolfcartparts.com/yamaha-wiring-diagrams

check the contacts in the forward/reverse selector for corrosion

Resister coil pack....Look up Buggies Gone Wild. Tons of info.