I have an '88 929 and when I start it comes on and then after 5 or 10 seconds, it just dies. When I turn the key, it will start again, but it keeps shuting off. I have changed the fuel pump and filter. Any suggestions would be great. Help me please.

Check the pickup in the distributor. Unplug it and have somebody crank it with an ohm meter on the two contacts it should go from zero to one. You can watch them running with a voltmeter across the two wires you should have 6 volts. If bad buy a rebuilt dist at nopi.