won't keep running????

[cruisingz]

need help! i just installed a re-built cylinder head on my 300d non=turbo.
valves a re adjusted(double checked). chain timing is aligned(double checked)
ip checked, drips at 24 deg, loosened injector line fuel comes out. checked compression all are 340 psi +/- 3%.
it's hard starting, when it starts to run, it only goes for about 10-15 seconds and dies, very hard to re-start and when it starts only goes for a few seconds. any advice would be appreciated...thanx...john
it's a 1981 300d