I picked up a 95 model 300trx 2wd from an old man down the street who literally drove to the mailbox and back every day for the past 20+ years on it, maybe 2nd gear was wide open for him. When he passed away I wound up with it and have been working on it to get it ready to use at the deer lease. It idles like a champ and runs around on flat ground with no load on it like a dream! Add a hill to the equation and it falls on its face. it never dies, just bogs down and surges. once you get back to level ground and off the throttle for a second or 2 it is good to go again until you get to the next hill. this can be a big hill or a small one, it doesn’t matter. any thoughts? it does it pretty much all the time after it warms up. fresh fuel, new air filter and an oil change 2 weeks ago.

carb issue? Maybe a clogged jet? I took the bowl off the carb and it is relatively clean, a couple pieces of junk and 2 ants, but otherwise it was clean (considering the age of the machine I am impressed).

thoughts?