Sounds like you need to spend some time with the manual..."messed with all three screws and loosened the slipper" will cause more problems unless you know what specific function each of the three screws is. The slipper clutch is for gear protection and traction control, and has nothing to do with keeping the truck still at idle.

The 3 screws are probably the hsn(high speed needle), lsn(low speed needle), and idle speed.

Hsn is accessable from the top, and has to do with fuel mixture from about 1/4 throttle to WOT(wide open throttle). Clockwise will give the engine less fuel(and oil). Common signs of an overly lean mixture is overheating(300+ degrees F.), cutting out at high speed, little or no smoke from the stinger...

Lsn is the screw that goes straight into the carb at the linkage, and controls the fuel mixture from idle to about 1/4 throttle. Clockwise is less fuel. Common signs of an overly lean lsn is high eratic idle, little or no smoke from the stinger...

Idle speed screw is the one that is located under the throat of the carb and goes in at an angle. Clockwise will raise the idle. When lowering the idle, check to make sure that the transmitter is letting the throttle close all the way.(does the idle drop when the brakes are applied? Then trim down throttle servo on transmitter)

Another possibility is that your clutch spring has lost some of it's springy-ness from heat, and it is engaging your clutch to soon.