my 1987 suzkuki samuria when driving or in neautrul  will give itself throttle like it has a mind of its own. i have checked for vacumleaks there are none. it will go from a steady rpm to wide open without the throutle blade or gas pedal moving and will not stop until you turn the motor off. when driving at higher rpm mostly like 3000 or more it will give its self gas for a second or 2 then stop and repeat over and over and in neautral will go straight to red line if you hold it at 3000 or more give or take a few hundred rpms. any ideas

sounds kind of like a sticking float.

There is an "idle up" circuit/solenoid that goes on when: 1)You're at altitude, 2) Accessories are turned on, 3)Heater on, 4) Lights on.  It could be malfunctioning and kicking on and off. I normally back it all the way off so it doesn't effect my system anymore. Look at the back of the carburator for a large flat nut with a vacuum plunger facing it. Back that nut off to adjust.

There are two idle adjustments besides the idle up circuit. Look at our FAQ located in the beginner / repairs sub-forum for more information.

-Eric