1997 S-10 2.2L humming noise under hood when applying gas and lower engine power?

First at idle I heard a cracking or breaking sound at the clutch, brake area in the cab. When I accellerated my engine started with a humming noise that I had heard once before. Before it was the front exhaust pipe so I replaced it and the humming noise was still the same. Engine started having acceleration problems at 50 and up. I took it to a repair shop and they said it was the gasket at the engine side of the egr pipe. So I replace the gasket and the egr valve and gasket. Same noise and lack of accelleration power. I also changed the O2 sensor. I had it scaned and the codes were: PO121, PO122, PO171, PO172, PO300, PO404, PO405, PO420 and PI1404. I started changing out parts. I changed the plugs and wires. Ran better that day then the next day same problems were back. I replace the TBS, Map and fuel filter. After that the engine started to do a puttering sound and very little accellaration. I replaced the fuel pressure regulator and checked the plugs and all 4 were covered black. I cleaned the plugs and re-installed them. I went to my last step and replaced the fuel injectors and cleaned the air plentum, which was very dirty and cleaned out the vacum ports at the TBS area and replace the PVC value and new air plentum gasket. Engine still has accelleration problems and humming. When I give it a little gas now it sounds like it pops in the air intake section and now I hear a tapping sound from engine front. My next step is to take it to a mechanic but with all that I have done what else could the problem be before I do that. Also, the CAT convert has been out for 3 or so years and engine worked fine up to this point.
I also was told by a mechanic that it could be the fan clutch so I changed that out too. Just one more mechanic trying to make a dollar to lead you to, "Well it could be, just to get your dollar instead of helping you with the problem to get it solved. If so, then they would have earned my/your trust so you will pay them to do your repair work and refer them to others so they can make the dollars we all need to do better.
PLEASE ADVISE ME WITH ALL I CAN DO BEFORE I PAY SOMEONE ELSE TO DO WHAT I DON'T KNOW WHAT TO DO YET, THANK YOU!