Need some help please. I am having engine issues with both trainers that I have.

First I have my Alpha 40 with the Evolution .46 NT engine that is supposed to be a great engine for a beginner. We (myself and my various trainers) cannot get the engine to run consistently. Initially we though it was a fuel line/air leak issue. I have replaced the tank and all the lines. Engine gaskets as well. I used dubro fuel line clamps to ensure that there were no leaks. The initial issue was that when I advanced to full throttle the engine would die as if it was not getting any fuel. We adjusted the needle valve so the mix was rich, and you can hear the engine slowing reving up as the mix was too rich, but when it got to full RPMs it died. Now we have adjusted the needle valve enough to run a full throttle, but when you go from full throttle to mid throttle, sometimes it dies as well. We have also adjusted the low speed idle on the carb as much as possible, the engine is not running consistently at all. Put in two new OS A3 glow plugs for good measure - it just won't run well. Any Ideas?

Second is an OS 40 LA that just will not run, it will start and run rough for 10-15 seconds, but once you remove the glow starter and get it to about mid-throttle it dies within a few seconds. I added a new neddle valve and lines are new, as this plane has never been flown. It is a brand new tank. As a matter of fact, I pressure checked both tanks for leaks - no issues. Replaced the gaskets. It will never get to full RPMs, it seems that it is not getting enough fuel to go past mid throttle no matter how rich we make it or adjust the low speed screw.

Any ideas? I have not flown since about October, and I am ready to just throw in the towel.