Usually a breakup at high end is it's starving for fuel...too lean...my Jato bogs down for first 2 maybe 3 highs speed passes until it comes up to temp (around 160 to 180 in my area) it'll do the bog at it's shift to second gear...If your up to temp then I'd richen it about 1/8th turn and do a high speed pass...hitting 2nd gear and running wide open...if it still bogs down at high speeds....richen some more but 1/8th turn at a time don't crank it out and don't adjust the low speed needle either...don't listen to the lhs store all the time cause they want to sell you things they don't always have your best intrest at hand they are more worried about selling you products...also you may need to adjust your shift point on that thing...my Jato wouldn't shift until it was like 300 feet away I also noticed alot of others had too reset it...traxxas doesn't have it set properly...but thats easy do high speed passes and adjust it as per the manual and you'll be set.


Also you say it's still running too rich? Whats the temps after a high speed pass? Is it shifting to second also...and best bet in your case maybe to reset the high speed needle to factory then lean down slightly til you get rid of that bog...but don't lean out too much. Alot try to run the 2.5's at extreme temps...remember max temp is 270.