Scott Bryan
when you replaced the cartridge did you use an original moen part? Sometimes we find if you do not use genuine parts you will have the problem you describe. The only other thing I can think of is you have some debris in faucet body. Flush it out while you have the cartridge out by having someone turn the water on. I hope this is some help.
Good luck,
Scott http://www.plumbingpartsdepot.com
