What kind of issues would a bad engine ground cause???

Its possible that the ground is the issue...but you ccant be sure. Bad grounds can cause all kinds of goofy things to happen like your wiper speed dial dimming your headlights instead of turning your wipers on, etc. Ya know, really weird things like that. But sometimes it can cause more normal problems like what your having. Make sure all your factory grounds and possibly any extra grounds where you may feel its nescessary are attached. ANd if that does not solve your problem..I would look elswhere. Possibly check your plug gapping...If I were you, I would wait till the new motor is installed and see if that fixes it (in the motor install you may properly reconnect an improper connection, etc)...if not than go from there.

I'd not look at the ground pathway as a fix for your issue. The computer has it's own dedicated ground pathway partially because it needs stability. If you had a motor ground issue, your starter would let you know about it.

I agree with Go-stang - do add another ground. I chose to add a 4 AWG cable from the motor-side of the passenger motor mount, and ran it to the passenger frame. This can help compensate for any deficiencies.

Good luck.