Can someone help with a DLE 20 Gremlin this has almost everyone at my field kind of stumped?

Get to the field, choke engine, engine fires. Unchoke engine, engine fires!!! Idle for 30 seconds or so and then open throttle up. run throttle up and down, engine responds just fine.

Now if I happen to get the plane in the air, it will run for maybe 5-8 minutes then uh oh Dead stick landing-happened twice, plenty of fuel left in the 14 ounce tank.

Sometimes, I just pick the plane up after doing all the above keeping it level to place on runway engine dies

Very difficult to get engine to start unless we let everything calm down for maybe 10 minutes or so then we go through the same problem.

I've pulled the gas tank three times now, checked the plumbing, checked the clunk, redid the plumbing-no change.

We pulled the screen on the carb, clean as a whistle.

Bypassed the engine cut off still the same issue.

New spark plug Twice

It's like it either is running out of fuel (but tank is more than half full), or the ignition just stops working after a few minutes. Battery voltage is kept at over 5v and less than 6v. Checked every time.

I'm gonna pull the engine off the plane and remove the carb I just don't know what is going on.

One last thing, I did reverse this carb, 180 degrees before installing. But like I said, the engine has run for as long as 8 minutes before cutting out so I don't think it is the carb position.

Engine bought from VVRC last December.

Anybody have any thoughts?

Thanks-

Larry