why can't I always accelerate from a slower speed. on 2001 Ford Explorer

idles hard, wants to stall when I come to a stop and recently will not speed up when I try to accelerate. the check engine light has been on for months after adding a gas line anti-freeze.

Asked by for the 2001 Ford Explorer
Most likely a lean code, if you can get it scanned and give us the code, it would be easier to guide you to the fix.