1986 Oldsmobile Cutlass Supreme Brougham Sedan V6 3.8 L, 231 C.I., Poor Performance?

I recently have been getting poor acceleration around 20 to 40 mph. And I noticed that around 40 mph, my service engine soon light comes on for about 5-10 seconds. So I pulled the code using a paperclip and received OBD 1 code 53. So I researched it and found out it had to do with the EGR parts. So I replaced the EGR solenoid/ no difference, then I replaced the EGR valve and gasket/ no difference, then I replaced the vacuum lines to the EGR parts/ no difference. Then I replaced the PCV valve and grommet/ no difference. Then it got worse to where it would stall out on me for 5 sec around 20 mph. Then it got to the point where it would quit if I came to a stop, the break pressure would build up then the car would quit. But if I put it in park at a stop and gave it a little gas it would keep running. Then my air management diverter valve rattled like crazy and when it started rattling the service engine soon light would come on, so I pulled the code and got a code 34. So I replaced that part and the two check valves, but it's still the same. I am lost. There is also a plug that is unplugged with a green plug with two wires going to it, one wire goes to the wiring harness and the other goes to the mixture control solenoid plug, I was wondering if anybody knew where it plugged into. Please help. And also for a side note during everything that has been happening, it has always started right up, and the car only has 28,000 miles.