Hey slickdude, NOW dont'cha wish ya went with a 4 stroke? This is exactly why I use the gassers. Unless yer an electronics expert then how are ya gonna fix it. And if you were an expert then you would know how to hook up a throttle to it. I would be having the same problems if I were using electric. I know almost nothing about electrics.
On your next build go with a 49CC gas engine. Use a large rear sprocket to keep the torque up and the speed down to under 20mph. A 20mph 49CC bike is an easy build. If your next build is a two wheeler then you could go with a little more speed if you want. And 4 strokes are quiet and very dependable and still probably cheaper to build then an electric.
Anyway, ALL this BS is just my opinion. I've always said, It's your bike, build it your way. Better luck on yer next build.
Big Red.
P.S. As long as you're using the throttle "button" you might think about putting an emergency cut off switch beside it. If it sticks again just cut the power completely off BEFORE yer in the middle of traffic. You could use a regular off/on toggle switch, as long as it's rated for the amps you're using.