[gmc396]

If it dies when you push in the clutch, but starts and runs with the clutch pedal up, the clutch mechanism seems like a likely culprit. Or did you mean that it dies when you push in the clutch pedal, then you release the clutch pedal while in gear and it restarts?

Yes, it dies when I push in the clutch and restarts when I release the clutch pedal while in gear.