a few things
		
		
				
				
					
				
		
			
				
					
	
		
			
			
				
					
 Originally Posted by 
tjh
					
				 
				This thread probably should be moved to trouble shooting . 
 What would cause the Idle to bounce from 500 rpm to 1000 and back again over and over ... when the vehicle is placed into reverse ?  It will sometimes do this while in drive . Park and neutral are okay , even with the AC on . 
   Until now , I have not had any engine problems . 
I can guarantee that it's not the driver playing with the accelerator.
			
		 
	 
 
My 2 most likely options vacuum leak, fuel clog
				
			 
			
		 
			
				
			
			
				"Take it up with my butt, cuz he's the only one that gives a crap"
 Carter Pewterschmidt