I have a 2002 Savage. I have changed the muffler to a SuperTrapp, now at 8 discs. After the SuperTrapp, I rejetted the carb with a Dynojet kit and used the 144 main jet. After that, I put the direct replacement K&N air filter in it. These mods have made this motorcycle a lot quicker, and it has tremendous mid-range acceleration.

Occasionally, I get a flat spot in throttle response.
In 3rd gear, the bike speed sometimes stays at 50mph no matter how much I open the throttle. Today, when this happened, I held the throttle wide open, it stayed at 50mph again, then suddenly started accelerating like normal. It was like something cleared suddenly.

I cleaned the SuperTrapp discs and this helped some but did not cure the problem. Could the SuperTrapp be plugging up in the glass section. Could the fuel filter screen be plugged? Could my NGK Irridium spark plug be failing? It has 1650 miles on it.

I'm looking for someone who has had this problem and what they did to get it fixed. ???

This motorcycle, when operating normally with all these changes, has a terrific mid-range power peak. It feels like a supercharger kicking in at 45-65mph in 3rd gear. In 2nd gear, it is scary between 30-50mph. It also has more pulling power from 45mph in 4th gear

I suspect a sticky needle in the carb.

Sounds like sometimes the slider is not going all the way up .Check for pinched diaphragm under the top cover.
Any way You will have to pull the gas tank off- check all the things You have worked on.