Well i went to the field yesterday and again the engine was back to the same old problem quiting the engine runs great at half thorttle and above then when landing with the engine at even a high idle it quits . yesterday i was doing loops and figure 8 right turns left turns low passes and the engine ran great but as soon as i cut the throttle down to less the half throttle to land it quit. other then putting this engine on ebay what else do i do. HELP PLEASE.

First you need to find out if it is too lean or too rich at the low revs, then people can give advise on how and what to alter after that.
If you point the model up slightly while running at low revs does it speed up or die right away?

If i'm understanding right are you saying at idle if i point the plane up does the engine stop . if this is right then yes it does quit .
I reset everything again today reset the high needles and adjusted the low in idle set the idle at a good low idle then ran the engine full throttle with the plane pointed up it ran fine then did the down pointing of the plane ran fine did the pinch test and had no rise or low of rpm then i lowered the throttle to idel and pointed the plane up and the engine quit.

Then it sounds to me like the low end is too lean.
The low end should be set a little richer than what might seem as ideal on the ground, it is set for a good throttle response in the air (no hesitation) and a less sensitivity for a lower fuel level in the tank, and/or a plane in a slight nose up position.

The high end might also be a little too lean. If there is no reaction to the pinch test then it will be too lean when it is in the air. You want to have a little increase when you pinch the fuel line, to make sure that it does not run too lean in the air.

(just to clarify an engine will usually not run on idle when pointed straight up, but when going from level to an inclined position the low end will go leaner and the engine should rev up a little rather than just dying.)

Gee, same thing happened to me but with a Saito 100. We play with the needle until we were tired of it. We open the carburator and it was clean. Finally someone at my club suggested an on board glow ignitor. I bought one for $94 and am going to the field fri to test the thing. I will let you know if it works.

He's blown at least three plugs in a new engine. It runs fine at the start, than it want's to quit later on. My first guess would be the tank is too low (raise the tank or rotate the how the engine is mounted or install a uni-flow fuel system). My second guess is a pin hole in the clunk line that gets uncovered as it runs low or a stuck clunk issue. Lastly, a restriction/kink in the muffler pressure line or fitting.

Oh, one more, Foaming fuel, isolate the tank with foam rubber.

Blown plugs, sounds like too much nitro in combination with a lean setting, what fuel has been used?

I don't have the .40 myself only a few the .10 but they both come from a time when 5-10% Nitro and 20% castor was the normal fuel. If you are running fully synthetic fuel in a plainbearing engine you can get problems with overheating.

This sounds like a hot engine, I have seen several LA's do just what you discribe when new and flow hard and lean. What type of fuel are you using, with or without some Castor oil? Many of these engines really need lots of oil to run well. I actually heard a K&B Sportster (45?) making noises and doing what you discribe, a little Castor/Syn. took care of the problem