Porsche 914 1.7 1972 runs great when first started

[BillyJoel]

I have a 72 914 with a pretty much stock set up. Car will start up fine when cold and rev up and idle perfectly in neutral. However, when the car is under load it completely cuts out and when it gets warmer it will just start up and idle very low for a few seconds then die (also adding gas at this point does not help). I checked my vacumn advance and it was stuck but I freed it up but it still does the same thing. Also, I plugged my Auxiliary air valve because it is stuck in the open position.

Does anyone have some suggestions on what this might be? I have checked the vacumn lines and checked for leaks in the intake manifold- both are negative. Also have new fuel injectors and fuel pump. Car is mechanically solid (valve adj. etc) haven't checked the dwell angle or timing yet because the car runs well when first started - about 3 minutes. then starts to bog and die out (occasional backfire in the intake=lean?)

Also car was sitting for 10 years.

Thanks and appreciate any response!