Loud Clunk when starting after checking for sludge

[OHFIVE9FIVE]

I opened up my valve cover to look inside for sludge and put it all back together and also replaced the spark plugs and now when I get a loud bang/clunk up front on the passenger side. I'm not sure what could have happened. I pulled the two plugs that run along side the valve cover, one that plugs into a sensor and another that is I think for the pcv with the run ring around it. It sounds like its from the intake area but i'm not sure. Any ideas?

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Is it possible that it could be a engine or tranny mount? Anyone?