Report "or high combustion pressures. All 4 O2 sensors are new as is my fuel pump. Could the MAF sensor be causing both of these issues? My book (Haynes) says it is not possible for the home mechanic to test this part. Is there anything else that could cause this issue? My MPG has been relatively normal - 16-18mpg, no noticeable idling or running issues. I did have a little difficulty starting a few weeks ago, but that went away"