Try to do a couple test cuts in Easel, that will help you determine if you have either physical or programming issues, or both.
If it's a physical issue, you may have belts too tight (or loose), the pulleys may be slipping on the shafts (check set screws are tight and on the shaft flats), the potentiometers may be too low (or high), or a few other things. It's hard to know without more details or pictures.
If it's a programming issue, well, someone else can help with that. I'm just an Easel user for now.
There are a couple videos addressing belt tension and potentiometer adjustment at https://discuss.inventables.com/t/x-carve-maintenance-troubleshooting-videos-add-your-own/13405 that may help you.
If you can post some pictures of the problem cuts, and a description of your machine (spindle type, speed, bits, etc.), we should be able to give you more detailed help.