Posted by: @tonybabiak

I'm having drivability issues with my 2000 Ford ranger 2.5.

What are the specific issues?

Posted by: @tonybabiak

Will one of the fancy high-end SnapOn scan tools show an issue on a vehicle this old with no code?

Quite possibly. However these days even inexpensive scan tools can be used for checking live data.

well the residue has worked its way through the system, potentially fouling up multiple components: filter, pump, fuel injectors, etc.

Rank old gas is a really bad idea.

Check the filter and run some strong fuel system cleaner through the system.

Thanks for your answer, Chuck. The drivability issues started when I poured three gallons of rank old gas in my tank. I then drove to the gas station and topped it up. The next day a valve stuck and a rocker arm popped out of place. After I put everything back together it will stall when it comes off idle too quickly. If I get away from idle without stalling it pulls very smoothly, no missing. It will, however, miss and buck badly at a steady cruise now. I had none of these problems before.  I'm on my second tank of gas since this fiasco started so I don't think gas is the issue anymore. I bought this truck when it had 13,000 miles on it and it has 28,000 now. That's not a mistake,  it has super low miles on it. I have to take the valve cover off again to replace the gasket but I'd sure like to get an idea of what's wrong.  I figure it's something I did or disturbed. Maybe got some dust into the MAF sensor?

Tony