Codes P3401, P3417 and P3433?

For starters my wife and I purchased this car on Facebook marketplace. I know not smart but we did it. I was told the car only needed a map sensor and a tune up. Got car home and changed map sensor, changed plugs, wires, ignition pack, and changed top hose on crossover. Had pin hole leak, got all this purchased and completed. Car started throwing 3401.3417.3433 codes. So I started casing wires to find the open circuit that's disabling 1.3.5 cylinders. Started by checking the 15 amp emissions fuse and it was fine. Followed the pink and black wires from the fuse Box to the wire harness. Followed clear up to the clip for the fuel injector harness. Still had good flow. Took plenum off to continue following circuit through the injector harness to a pigtail just past the 2nd injector on firewall side of fuel rail. The pigtail went about 3 inches into a plug of some sort just laying on top of of lower intake. Since there was limited amount of wire to me it seemed like needed plugged in somewhere real near but there was nowhere for it to plug. So I started researching what and where this plug goes.I noticed on some lower intakes for the 3.9 there was a hole in top of lower intake right in spot that this plug would fit. Between the 3rd and 5th cylinders. So instantly I figured it's got the wrong lower intake.I ordered a new one that has said hole for the plug. Which I even bought a Haynes book to find out what the plug was and it didn't even say! I then went to a local junkyard that you pull parts yourself just to find other impala with 3.9 and only found 1 with same engine.20 others were 3.5's and different.I looked at model tag under hood and was very close to mine almost exact. First thing I noticed was the alternator was on backside of engine by the firewall. Whereas mine was in front of motor by radiator. Weird I figured. Took plenum off and seen that the mystery plug was indeed plugged straight down through top of intake. After I got back home I felt my car possibly has wrong intake so I ordered a intake with plug hole.I even tried finding another 3.9 with alternator on front like mine and couldn't find any diagrams or even pics of 3.9 where my alternator is at.I have pics of my 3.9 and pics of junkyard 3.9. If want pics.