Tahoe suddenly running like crap

[The Russian]

So I transitioned from e85 back to regular unleaded from kroger last wednesday. I filled up with the low fuel light on so there might have been 2-3 gallons of e85 left. The next day when I was heading home from work I noticed a bit of spark knock and it didnt seem to pull like it usually does. Took it over to my Dad's house and he drove it WOT down the street and instantly got a flashing check engine light. Pulled the code and got a p0300 random misfire code. We made the assumption that Kroger's S*** tier gas was the problem and added a bottle of ISO-HEET. I went over to see some family saturday in it and got another code P0101 MAF outside parameters. Cleaned the MAF last night and it ran perfect for 2-3 min at idle in the garage but the second I pulled out to go test drive it, all of the issues came back. Exhaust has a lot of sulfur in it. I have about 3/4 tank left in it. Should I attempt to drain the tank? I have limited tools at my house and no jack so I'm kinda limited on what I can accomplish. Any help would be appreciated. I would love to see if the cats are clogged, but the exhaust is still putting out plenty of warm air like it should.

 

[DMGun]

I am thinking reset by removing the negative battery cable for 10 minutes then reinstall. Key on for 30 seconds. Start and idle 1 minute with everything off. Put in in gear and hold brake for 1 minute. Turn on Air conditioner and let idle for 1 minute... That puts it in a base strategy and should learn from there the proper air fuel / timing strategy.

 

[MRM]

I would top off with some high octane and try again. When I used to work on cars it was good practice to only "fix" one thing at a time. If it was good before the switch, I'd try different gas and see what happens. Maybe the computer hasn't made the switch yet.

 

[CBH13]

sounds like it has ebola, take out back a choot it

 

[jdm333]

I second DMGun's suggestion. Your computer had likely learned how to run on e85 and is confused by the higher energy content of the new fuel. Do you have a obdii reader to see if you ate getting into closed loop mode?

 

[ARCman47]

What year model Tahoe do you have??

 

[HighTower]

U mention exhaust smells like sulfur; possible bad/clogged catalytic converter. Does it feel like it can't push the exhaust out? Possibly idle jus fine but stumble with a load?

Depending on the yr, those vehicles are notorious for leaking intake gaskets which cause a miss and will throw lights like u mentioned.

for some reason I'm not suspecting it to be the gas

 

[8675309]

i try to fill up at the same station every week.

 

[The Russian]

2005 Tahoe PPV flex fuel. I replaced the intake manifold gasket in March when I replaced the knock sensors in the valley. It feels like it can push the exhaust out fine. It smells rich after it warms up, but that is amplified by it being garage kept.

 

[ARCman47]

2005 Tahoe PPV flex fuel. I replaced the intake manifold gasket in March when I replaced the knock sensors in the valley. It feels like it can push the exhaust out fine. It smells rich after it warms up, but that is amplified by it being garage kept.

Might try some decent fuel treatment like SeaFoam or Lucas ... go somewhere and get GOOD gas.. yes all gas is NOT the same. My friends dad hauled fuel for 30+yrs. Top tier fuel, something like BP or QT or Exxon. This would be something simple to try.