as above, check the basics, but..............................
if it stumbles, bumps, pops and bogs, then suddenly comes on smooth at about 3K. I feel your pain. what you're describing sounds like more than just mis-jetted. and sounds exactly like my 3.0 was running.
my problem was dirty idle jets. easy to fix and costs almost nothing.
replace fuel filter first, with a good one. remove mains and float plugs and idle jet holders and let carbs drain. run pump for 30 sec to flush carbs. put mains and plugs back in.
remove idle jets from holders. have a look, I bet you see some bit of something in a couple of the jets. blow clean and look to see a clean hole. re-install in holders and screw holders into carbs.
even money your problem is solved.
your jetting is the same as my 3.0, except I have 185 a/c. and it runs kinda rich, but I like it that way. when you get the big issues sorted, get a Gunson Colortune. best tool ever to tune six individual carb throats.
see post #42 on this thread.......
Gunson Colortune / Experience Any Problems?