I'd pop off the linkage at the carb and see if the slide will close then. The idle stop screw should keep it open about 1.5mm. If that's okay, then it could be your linkage is out of adjustment. It might also occur if your carb slide is rotating. If the slide rotates, the stop screw is no longer in the groove. Normally this manifests itself by killing the engine when you apply the brakes. Slowly (!) turn the screw in (clockwise) while slightly rotating the slide back and forth until you find the groove, and set the opening to 1.5mm. Warm up the engine, set your high-speed needle. Then set the low-speed needle so it doesn't bog off the line, and use the pinch test. When the two needles are set, fine-adjust the idle stop screw.

Mine was running lean when my idle stop screw o-ring failed; but you could also have a air leak somewhere else, though that wouldn't hold your slide open like that.

I just reread your post...make sure your throttle adjust bias knob is correctly set on the transmitter, too! (Do that first!)

Oh, and welcome to rcuniverse!


edit: edited for speeling [X(]