When I step on the gas the motor will rev up then hesitate for a second then continue to rev up..It's a holley 4150 with stock size jets and powervalve.. Fresh rebuild... bought boat in Vegas and live in  ogden, ut.. 4500 ft.. Where am i off in the jetting... Primary??? Secondary??? Powervalve??? Help    Other than that it runs on a dime.. Plugs are a nice chocolate color...

What size acc pump is on the back?   50cc's front and rear would probably knock that
right out of it.
It sounds like your plugs show good mixture being chocolate.   

I ran in the SS nationals in Odgen in 1970. Couldn't start the motor (427) BBC. One of the Mang boy's came by and handed me some jets, I was running 80 they gave me 60 and ran. Never gave a thought of the sea level change.

I ran in the SS nationals in Odgen in 1970. Couldn't start the motor (427) BBC. One of the Mang boy's came by and handed me some jets, I was running 80 they gave me 60 and ran. Never gave a thought of the sea level change.

20 numbers is a huge jump 

I wouldn't hesitate to make a 10 number change to what you have and use that as a starting point.

2 numbers is a fine tuning change, if it won't run you need to be make a big change to get in the range.