It could be a fuel contamination.  I found the problem you describe on a couple cars  not to long ago . They put the wrong gas, it was like a very thin oil mix with gasoline. Check the fuel just to eliminate that.

With your Maxisys you can check the fuel pressure too.

http://abc7.com/news/ontario-station-mistakenly-pumps-diesel-instead-of-gasoline/1170439/

 I think because 95 percent of the cars on the road use regular gas instead of premium , the mid grade and premium fuel sit in the underground tanks much longer than it did years ago when more people needed to run the higher octane fuel to operate without engine ping.

 Those cars did have problems with the high pressure fuel pumps. There is one on each bank. It seems unlikely that they both would go bad however.