4.6? The o-rings on the needles are not very good and prone to cracking, then they suck air, make a high revving, lean run on idle. Sometimes they will not accelerate at all. I keep new o-rings here. If you have some teflon paste, you may need to seal the lsn and the hsn needle both. Apply a small dab of paste to the threads only, do not try sealing the o-ring itself with it. I have also had the "do not move" mid range needle with bad rings. Other places to look would be the backing plate, base of the carb and front bearing seal. I take it the carb slide is still moving in and out like it should. BB