nope, not a user error. i too had one and loved it until i couldnt keep it tuned between heats. retuning for each qualifier got old fast. im not the only one with this problem either. this is why the people who run the 8 port and swear by it also recomend buying an o.s. rg carb. ive heard they cost about $80 but havent checked into it myself (so dont jump me if im wrong!).
after about 2-3 weeks of fighting that motor i got a used o.s. v01b (another headache and long story) but thats when i decided to drop the $ for a good motor and i got an RB WS7II. long story short- i hated it. oh...im rambling...

for the $ my vote would be the rg. great power and very reliable.