I have an unusual problem. The mower will stop all of a sudden, if I pull choke it keeps running, but will do same thing latter. I have checked fuel pump fuel line from tank to carb, all other associated parts. cleaned carb checked fuel solenoid .  I have a mechanical back round but this has got me stumped. Any ideas would be appreciated. 
  
Thank you
	
		
			
		
		
	
			
			Thank you