2004 Suzuki Verona • 87,000 miles

So car has been running rough lately. So rough that cant drive. When I took it to Firestone they told me the ECM/PCM was bad. At that time the only code I had was PO430. Now I also have PO403, PO404, P1382, PO305, PO650. So they question is could all but the PO430 be cause by the supposed bad ECM/PCM? And other that taking the car to a dealer or repair shop is there any way to test it? I did find a $1500 ECM for $110 at a wrecking yard and called a shop to find out price to program it and is also $110. So should I spend the money on a new one or save $1400 and get a used?
October 19, 2012.

Have the EGR valve, Oxygen sensors and Catalytic converter checked out-Have the exhaust system backpressure tested-start here

Oct 19, 2012.
P0305 Cylinder 5 Misfire Detected
P0403 Exhaust Gas Recirculation Circuit Malfunction
P0404 Exhaust Gas Recirculation Circuit Range/Performance
P0430 Catalyst System Efficiency Below Threshold (Bank 2)
P0650 Malfunction Indicator Lamp (MIL) Control Circuit Malfunction
P1382 Wheel Speed Sensor Malfunction

With so many codes present, I doubt it is a faulty PCM. I would suggest getting a second opinion. Check the PCM harness connector for looseness, presence of water or contaminations. Ensure all ground circuits are good. Erase the trouble codes and recheck if any comes back.

The EGR system could cause the first 4 fault codes.

Oct 21, 2012.