Yea to much nitro for the mvvs use 5%, as far as the muffler, their the same as the rossi muffler and it is about the best their is. Sound be me like you ruined the engine with to much nitro.

Your 91. You say you can go to idle then dies when you advance to full.

Doesn't it surge then die or just die?

If it surges then dies then your idle is rich

If it slows down and dies it's lean


The best way to check this is at an idle pinch the fuel line, if it has a remote neddle valve pinch the line between the needle and the carb.

Again if it surges then dies then its rich slows down and dies it's lean

Another way is to let it sit there and idle

if it gradualy slows down and quits then lean the idle. if it speed up before it quits then richen it.

After the low end it set reset the high end. advance to full. lean out the needle until it peaks then back it off about 20 degrees.

Trie the transistion a couple times. it sould advance from idle to full fairly smooth

Have another guy hold the model pointing it up 45 degrees it shouldn't change rpm

This is the one mistake I see again and again is no one touches there idle screw. your idle screw can affect the high end as well.
Otherwise clean everything out and try another glow plug


BEfore you go out the feild next take some canned air and blow out the venturies on the carbs of both engines