it ran good 2 weeks ago then the roller on the end of the bar burnt up and i put it up then the chain break broke off i bought a new bar and put on it and when i started it it ran like crap like it had water in the gas,thats when i found the lose carb mount and its ran like crap since
The chain oil and bar problems are not related..
The loose carb mount allows un-metered air into the engine, and is the cause of the high rpm. Get a new gasket, base or collar, that will hold the carb on air tight.
Back off the throttle plate screw so the buttery fly is closed.
With great care to stop when the mix screws stop turn them both in till they just stop, turn no more in... These screws and their seats in the carb are delicate.
Turn each one out 1 full turn. This won't be right, but should be in the ball park to run.
Try to start the saw. Try to determine if there is enough fuel for the saw to idle. With the "L" screw. turn it OUT more for more fuel to a best idle.
If this doesn't work turn the throttle plate screw IN 1/2 turn to open the throttle plate a smidgen. With a sliver of note book paper apx 1/4 wide trimmed neatly use it as a feeler gauge between the throttle plate and carb body, to be sure the throttle plate is slightly cracked open.
Try to start the saw again. If it runs and idles adjust the "L" mix screw again for best idle rpm. When you have best rpm turn the "L" mix screw out a little more, but not so much as will flood the mix. You don't want to hear a change in rmp to lower than best rpm.
You need that bit extra fuel to get higher rpm range from a stopped chain.
Then go to the wood pile with the screw driver for the high speed screw.
See if the saw revs up just as you would begin to cut fire wood. With the saw cutting get best high speed rpm, and again go OUT with the "H" speed screw to as high a rpm as you can get set to the rich side.
Note the best RPM cutting will be overly lean, and will burn the piston. You need to be slighty rich cutting.
I hope this makes sence to you.