A couple thoughts.

This just started happening since you replaced the sprocket? Is it possible the chain is now too tight, or mis-aligned? The sprocket has the same number of teeth?

Also, I think many people make the mistake of assuming their opener is defective, when in fact it's the door tracks or springs. With the opener disconnected, does the door open and close easily throughout its range? If not, it could be over-stressing the opener and causing it to stall, regardless of how high the force adjusters are set.

David