Vehicle starts but when key released from start.

Check that the ballast resistor is not blown if fitted, also check that there is power at the coil pos with the key on run, let me know what you find.

Or you can try this power the coil from the battery positive post with a jumper wire straight to the coil's positive terminal-if it continues to run-check/test the resistor and the ignition switch as suggested-

Are you still having problems and need more assistance-Let us know