95 Blazer missing and rough Idle.

Hello all,
I have a 95 blazer that all of a sudden started missing. It just had a semi-new engine dropped into it. We where on our way back from a trip when it lost power and would not climb hills. On the flats it will do 75-80 MPH. It has no power. I thought that it may have been bad plugs or wires. I pulled the rear drivers side plug and the electrode was missing. (See picture)

http://www.aiorejects.com/images/plug1.jpg
http://www.aiorejects.com/images/plug2.jpg
Sorry for the crappy pictures.

It doesn't smoke but it does smell like gas. Also it pings really bad. I have changed the plugs (PITA) and it still did not help. The service engine light has not come one. To me it sounds like it jump time but I don't know. Thanks for a suggestions.

get the codes pulled hopefully the engine isn't completely destroyed there are a few things that cause detonation such as a lean condition, bad knock sensor, heat range too high on plugs. i would do a compression check before throwing parts at it it's very possible you dished a valve or cooked a piston.

Well I took it to my dad and he thinks that it sucked a valve. I will call the shop where they put the new motor in at. Was only done 2 weeks ago. I don't know if they will do anything. Oh well. Thanks for the info.

Ok well just got back from the shop. The guy thinks it's the connecting rod. So, they are going to pull the motor and replace it again.