Recently, I've had a problem with my plug wires popping out of the valve cover.
I was never a problem until last week when I:
1) Cleaned the crabon from the EGR Maintenance ports on the intake.
2) Replaced the distributor.
3) Replaced the valve cover gaskets.
4) Replaced my plugs.
5) Replaced the PCV valve & hose from TB.
Now, every time I go anywhere the middle two plug wires pop out! Do you think it might be time to replace the wireset?
Honestly, I'm just alarmed that that much pressure is backing up into the plug housing during normal operation. Is this normal?

 

If the plugs are properly seated and torqued, I would guess the engine blow-by is getting past the spark plug tube grommets and pushing the plug wire off. You would most likely have oil in the tube, too. Other than that, do the wires click or lock into position when you seat them? The metal ring inside may be bent and it doesn't grab the plug end enough. Vibration could work them lose.

 

or the little finger inside of the plug wire is loose, very common problem.

 

Actually, I think it's a combination of both.
The plug wires do come off pretty easy, so I think I need to replace them.
I also have oil in the plug tubes as well. Since I replaced the valve cover gasket (including tube gaskets on top of the tubes) I imagine it's due to weak or failed seal on the bottom of the tubes. I've checked out the fix for that. It doesn't look like something I can do in the parking lot of my apartment, which means my mechanic is going to charge an arm and a leg.
What would happen if I just let the grommet replacement slide for a while? Would that significantly impact my performance (and more importantly, gas mileage)?

 

mine did that also, after i changed my spark plugs...Popped out while i was driving and threw a CEL, but I just took the spark plug out clean everything (the plug,wires) since then its' been fine.