Truck Forums - Unknown Truck part

I had my manifold gasket replaced at a shop 2 years ago. Then I did alot of repairs and upgrades myself with ASE certified friends. Im gone on the Great Lakes ships usually 5-10 months at a time. I dont get to drive much. Over the last year or so Ive noticed my truck stutters if Im hard in the throtle @ the shift points. Once or twice from 1st to 2nd. Then really bad going from 2nd to third. Its like it has a governer or cant decide if it really wants to shift. The other day I was looking under the hood doing a tune up and noticed this (photo below) thing said on the top part "Bottom" Should I flip it over? One of the hoses goes to the front of my throttle body , two seem to go to my front end, and the other is a larger diameter and goes down below where the driver is to the rear. (its a 4x4 96' dodge 1500, 360ci engine) Ive been to many shops before and they cant figure out why it wont shift properly. I had the trans rebuilt by a professional shop and they still are at a loss as to why.

Pic of the item, not sure what it is. The Haynes manual only has two things it might be. An EGR item or part of the EVAP. Please help. If you read the picture after clicking on it, youll see it seems to be upside down.

I have turned it over, now I get an error code. "P0443 Evap purge selonoid circuit" & "P0441 Incorrect Purge flow" If it says "Bottom" And I flip it over why am I getting codes now? And when I switch it back it wont clear the codes even if I disconnect the battery. Omg, Im gonna go nuts.

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Thanks in advance for any help on this.