I lost my pcv valve grommet in the valve cover and i cannot remove it without taking it off, will it hurt anything if i leave it in there ?

 

it could do lots of damage... If it gets stuck between the camshaft and a valve it could result in a bent valve although likely but more likely is it will get shreaded and plug up some of your oil passages

 

That dont sound to good O_o
I really dont want to remove the upper intake manifold just to get a grommet ><

 

Think of it this way: take some time out now to fix your mistake, or put your hands on the counter and bend over when they start telling you how much it will cost to fix everything it destroyed? lol Yea I would definitely get that sucker out of there that could cause some serious problems.

 

I would remove it just to eliminate it causing any damage else where!