bad miss at full throttle

I have kymco mongoose 90 (taiwan made) it has bad miss to it when I give full throttle,seems like its starving for gas or fire.It still runs at full throttle but sounds funny like it has quick missing sound and it wont reach full speed.When i let up on the throttle a little bit it runs smooth as silk with no miss.I have cleaned the carb and tried adjusting the mixture screws every possible way I know but still have had no luck,also have cleaned tank and new gas lines...Anyone know what the problem maybe with this thing its drove me nuts trying to fix it?  

either timing or valves, or the head gasket,  these machines have a habit of blowing the head gasket.

also you are supposed to re-torque the head bolts after the first month of riding.  

would it have anything to do with the speed sensor control?It has cdi speed control assembly on it  

it is possible.  

ok, I'm thinking its an electrical problem I took the plug wire and stuck a screwdriver in it,then grounded myself out.The spark seems to be kinda weak when cranking it over,it does make my arm twitch a bit but nothing I cant with stand. Shouldn't this knock the piss out of me?also its more of a bad hesitation at full throttle like it wants to run but lacks on something.It also has a cdi speed control asessmbly box on it could this have something to do with it and is there a way to bypass the speed control?  

normally there is a connector coming from it that you just unplug but some are designed not to run if it isn't plugged in.  so try unplugging it and see if it will still run, if so does it run better?  

you can test the coil by using an ohmmeter, put one lead into the spark plug cao and the other on the other wire.

it should read between 13 & 15 ohms.