I have a G16E Yamaha cart. All batt replaced. The prob is after driving for 5 min and climbing a hill the cart will stop and you have to let it sit for 5 min b4 you can get it to go forward again.

seek local help but sounds like it might need transmission looked at

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.

Are the batteries fully charger? You have tested them and verified this is the case?

Sounds like fuel starvation, change the fuel filer.

contaminated fuel, fuel filter clogged, injector ports caked.

Most modern automatic transmissions have a chip in them that will prevent the car from downshifting, say, into first gear when you're moving at 60 mph. Still, I wouldn't try it. When climbing a hill, only downshift if the AT can't decide which gear to be in and switches back and forth--choose the lower one. When descending use brakes to decelerate. However, once you've braked, do use a low gear to coast in, to prevent you from freely accelerating down the hill.
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GM Tech2 GM Diagnostic Scanner With C card

check for a pluged cat converter

sounds like ecm lost signal from key

This is a Direct result of a Bad Alternator. You can Run on what is left in the Battery for a Little while and if it sits for a While the Battery will retain enough Power to Start. You may need a New Battery in Addition.

There is an ignition switch in the steering wheel column that maybe it