How about in neutral?
1. Test it with another tachometer.
2. If you are not getting enough RPM it's time to do some trouble shooting. Could be anything from the linkage/throttle to fuel to exhaust.
Do some research, make a list of possibilities and start checking them off.
It will rev higher in neutral. I donít have a spare tec? That would coast quite a bit for a test procedure. I think I will spend some time this winter jacking it up a bit. Thanks for the help