My was a pain in the rear too... I catch my knuckles every time on the body post and I get a couple of blisters because of the handle, plus the process to loose the engine take like 2 full weeks on small ajustments here and there []

What I can tell you is just hold there and take your time... at the end every one is going to be happy, I will list what happend on my in order so maybe you can follow the same line and get it working 100%

1.- Check the glowplug, fully inserted and working fine
2.- Screws that hold gas tank, my was really loose and the gas tank was jumping like crazy (not sure if that was a problem or not!)
3.- Idle screw too close from factory, I open always a little more than the 1mm recomended my Mg16 Idle fine now
4.- The tube that comes from the muffler was coming off every time that I try to start the truck, so I re-route the line to the other side of the cylinder head now It's holding fine
5.- My engine was hydrolocking bad every time up to the point that I have to remove the cylinder head to see what a hell was hapenning, when I was doing this I found the backplate on the starter was loose way too much so I get it back on place, after that the engine stop locking, not sure if that was why it was doing it that often but loose parts are not good!

I experience like you bubbles on the gas lines, I think have to do with the quality of the gas lines, they come really easy on my mg16 so I'm 100% sure they are part of the problem but I have being to bussy at work to stop at the LHS and get some new tubes... The truck start easy now after 5 thanks but still I have air in the gas line and when the gas thank is almost running out there is too much air on the line and the engine just die and waste like a little less of 1/4 of tank [:@]

I'm going to work on this problem on 3 stages: changing the tubes, then If it don't get better I will work on fit a tunned pipe for .15 and if its not working will look for a different was tank.