I'm not a mechanic but know how to read the P codes and have the genuine thick 2003 Chrysler Repair manual.

Here are the onboard codes:

13.3 - O₂ Sensor Circuit Slow Response (Bank 1, Sensor 1)
17.1 - Fuel Trim System Lean Bank 1
44.2 - Evaporative Emission (EVAP) Small leak detected (often due to loose/bad gas cap)
45.5 - Evaporative Emission Control System Purge Control Valve Circuit Shorted

Every time I start the engine, the engine RPM's seem lower and engine is struggling (or suffocating) to reach proper RPM. It started 2 days ago when the vehicle would not downshift to 2nd while driving at low speeds. At first I suspected the transmission but these symptoms persist while the car is parked + codes indicate otherwise. The issue is getting worse. I am unable to barely rev the engine and now it is running rougher and rougher, perhaps due to bad air/fuel ratio? I've looked under the air filter for blockage but it looks clear.

I have 3/4 tank of gas, checked the gas cap and re-secured it. I could not see any hoses that may be broken or come loose. Charging system is working but with the reduced RPMs, I'm trying to minimize cranking.

Does this sound like something an average person can fix? I'm planning to have it towed, earliest appointment is next Wed AM. I'd be overjoyed if I could cancel the appointment and save hundreds of dollars.

Any constructive advice is greatly appreciated!