Last year the iron duke was running great. I parked it for the winter and did a bunch of suspension/driveline updates. I have taken it for a few test drives recently and the iron duke seems to be running a little off. My issue is that at lower rpm, the engine seems to bog down and feels low on power, especially under load on hills. After I get over ~2500 rpm, the engine perks up and seems to run as expected. The engine starts up good, and idles smooth as expected. One thing I noticed is that the tachometer reads high and is erratic when the engine is hesitating (probably about 2x actual rpm). So, during acceleration, the tachometer climbs up to a false reading of ~4500rpm, then abruptly drops to 2500rpm (what I believe to be the actual engine rpm), and then the engine perks up and accelerates as normal. I am pretty sure the tachometer is working properly because I tested 2 different ones and got the same result. Timing or vacuum advance issue? Any help would be appreciated.