Misses, backfires when going up hills

You got a bad connection to the fuel pump inside the tank.

Code 171 is system to lean "1" code 174 system to lean "2" code 420 catalyst system efficiency below code 530 a/c refrigerant pressure sensor "A" sounds like o2 sensors are bad or vacuum leak

Could be that your cat is clogged up,the way to check is to remove and look in both ends,mine clogged up and caused my head gasket to blow between cylinder 3 and 4 on my 85 Nissan 720,part of the inside came apart and was blocking the air flow,causing my exhaust plugs to blister.

Check engine codes for misfire data--should say which cylinder.

The OverDrive band is worn out.

Needs a complete rebuild to access the OverDrive band.

Something like this is often a stuck or poorly sealing valve. A Vacuum gauge is the least obtrusive way to notice vacuum changes. If a cylinder fails to seal, vacuum will reflect the loss of compression and it will result in a bounce on the meter.

Backfiring occurs when uncombusted gasoline gets into the muffler. You will have to figure out if the engine is flooding and why (can be a lot of things - poor ignition, problem with fuel pressure regulator or an injector, vacuum leak, etc.). Existing trouble codes (DTCs) will help you diagnose the problem.

sounds like the catalydic converter is plugged/partial blocked- replace

Driving down several hills today and my car decelarated. It would not coast. I had to use gas going down. This happened yesterday as well. Today, the check engine light came on

Could be vapor lock in the fuel system. Next time it does this, stop and try removing the fuel filler cap... Hope this helps...;-)