igniton fault???

hi i have developed a fault with one of my golfs. its a 83 1.5 auto cab. has always been a good runner till i took it off the road to drive my new addition (83 gti mars red). sometimes after driving an parking up then trying to start again i'd turn the key but nothing as if trying to start in drive although def in p or n. you get ignition lights but no cranking. once left for x number of minutes hours days it will start again fine. since trying to start again for an mot recently after being parked up for a few months it cranked over then eventually fired up but as soon as i release the key it dies. if i continue cranking it it will rev up and run (with starter motor still working) however if i engage d or r on the gears it dies then too. i've swapped the igniton switch at the bottom of the barrel to keep the same key but still has same fault. is there anything else i should be checking or changing? is it worth swapping the ignition barrel aswell?

any ideas would be gratley appreciated as would like to drive it to volksworld 2012

thanks in advance guys

CHECK THE EARHT CONNECTION ON THE SOLENOID PART OF THE STARTER,ALSO CHECK THE SWITCH UNDERNEATH THE GEAR SELECTOR,ALSO CHECK WIRE FROM IGNIGTION TO COIL.START WITH THESE AND YOU SHOULD FIND PROBLEM.HOPE THIS HELPS

could also be the starter is dying, or you need to do a relay mod on it. see this thread for more info:
http://www.vwgolfmk1.org.uk/modules.php?name=Forums&file=viewtopic&t=112538