I had a 148..the best way to adjust the needle is place the engine just behind the rear wheel of a nice pick up truck. Put the truck in reverse and nail the throttle, then put in drive, floor it again. Repeat as necessary until the stress and frustration is gone. (could be doing this a while, so be forwarned)
When you start enjoying yourself and catch yourself smiling uncontrollably, stop and get out, pick up offending engine, and toss in nearest trash recepticle.
Worked for me, your results may vary.

OK, the other fix is buy a ASP 108 carb, install and fly. Price is about 35 bucks.
Problem solved. The best thing you can do with the stock carb is drill a hole in it and put it on a key chain...no foolin' mine is still on my key chain after a couple of years.
Great conversation starter.
True story, no foolin', fact Jack.
The 148 is a stump puller when running right, but usually kills your favorite plane because of Many Dead Sticks.
FWIW, I was determined to get every MDS running perfectly..I took it personal and eventualy owned 8 MDS's...sold everyone except 2 68's....which I'll be selling this fall with all my other glow.
Good luck.