im at almost the same elevation as u, i used to have the same problem. what i did is run 147.5 main, and the needle one notch from the bottem( in the summer) in the winter i would have to go a 152.5...i played with the needle in the richest position and it didnt seem like i gained anything from the fourth position...

 

the only common bog the TMs ever had was right off idle, and was only due to de-activation of accel pumps.

being one groove off on the needle or a couple main jets off will not cause a hard stumble, but the pumper can.

you are running the pump, but if the pump is running too rich it will cause this type of issue. first confirm you have the #50 nozzle in place, and also make sure its aimed right at the needle for break-up and atomization. after confirming this, check the pumper travel limits. there are two screws that control the pumper travel - one is on the white pump lever, it controls when squirt starts. the other is on top the carb, a tiny screw on the right side that sticks through a hole in the carb cap on top, it controls when the squirt stops. you want the squirt to begin immediately off idle, but stop after 1/3 throttle travel, you don't wanna squirt to 1/2 throttle.

be careful of the float level while taking the bowl off to check the pumper nozzle size, and be certain not to damage the pumper o-ring re-installing and put some lube on it prior to sliding it in.

this is my first guess...a quick confimation of suspision would be to to simply slip the spring off the pumper lever with your finger to deactivate it. this will cause the infamous lag coming off idle, but if the pumper is to blame for the bog at 4000rpm then that will be gone. try it and see, and get back with us..

 

what kind of lube should i put on the pump nozzle??

 

I just mean a little dab of grease on the o-ring prior to pushing the nozzle into its hole, to keep from scraping or tearing it.

 

i don't run the pump but i also run a rather large pilot jet, never needs the choke but it also doesn't stumble down low. seems i'm at 47 on the pilot

 

Im gonna try playin wit the needle first and see where that gets me, hopefully it isnt the act pump, it feels good off the line, where the pump kicks in, its just at a steady throttle at 5000 rpms it lags unless i punch right thro it

 

if you don't know what pump nozzle is in the car, you need to know. you don't wanna band-aid a rich pumper by leaning the needle. its no harder to confirm the nozzle size than it is to change the needle, just 4 screws on the bowl vs. 3 screws on the top cap. if you got the #50 nozzle then that's all good and move on to the needle. I only suggest it because many TM's have been sold for the DS with the #70 nozzle in them from factory and its way rich and causes definite stumbles at mid throttle.

 

How do i find out which one i have?

 

it says on the jet.

 

check PMs'