DLE 20 engine only quits in flight in less than 2 min., will run 5 min. on ground no problems. pick up plane ad move it around with motor running at 3/4 throt. and it works fine.

Your question? Some particulars about the plane the engine is mounted in will help.

Sounds like it just needs more fuel.

I have several DLE 20CC and bigger engines. Ensure your fuel tank is 3/4 and above when you take off. Pressure decreases as you ascend and it sounds like your plane is losing fuel pressure once airborne.
Also...make sure your ignition battery doesn't have an intermittent connection issue: once airborne. All you need is the battery wires to move ever so slightly and it will kill your ignition = killing your engine.
Remember gas planes vibrate a lot, and all it takes is one little solder crack you cant see and it will kill ypur engine while flying yet seem fine on the ground, leaving you scratching your head.
Hope this helps. Keep us posted!...interested to see what the problem turns out to be!

Sophia
RC Pilot and builder over 35 years.

rwahl,
Join date 2004, yet this post lacks what I would call minimum required information. OK Sooooo....

Like the following:
your level of gasoline 2 stroke tuning, beginner, expert? (or did someone else tune your engine)
what prop are you using?
what fuel oil ratio are you using?
how is the engine mounted and cowled? ( a picture would be best)
what are your needle settings?
what is your fuel tank setup?

Answering these questions would help in a solution from this community.
Respectfully kmeyers