P2178 Chevrolet -

Question

P2178 code system too rich off idle, replaced 02 sensors and cleaned maf sensor. Vehicle downshifts from overdrive when under slight load and doesnt want to upshift until you feather off the gas pedal.

Answer 1

P2178 Fuel trim rich at cruise or acceleration

When you have this code P2178 disregard any transmission symptoms and the ABS and traction control  will be disabled. Check for any exhaust leak prior to the 02 sensor, and especially any charge hose that may not be properly connected. A charge hose not properly connected or leaking.