I'm trying to remember the size of the plug for the exhaust manifold when deleting egr on a 94-5 driver's side. I was thinking a metric 19? Mine fell out yesterday and I can't drive it to the store.

 

should be 22mm.

 

To the better of my knowledge, no such thing as an inverted flair metric thread. With that stated, they (metric thread plugs) have been used effectively. HOWEVER, the hole being plugged, is NOT machined with a metric thread, just so ya know. Doing a good/thorough search will reveal this fact.