Bad gas or coincidence

[4.6EXPLORERFAN]

So my tank was about on empty and I stopped on the way to work and put in a little more than a half tank. I had some Lucas Oil fuel system cleaner left(about half a bottle) and decided to add that at the same time. Just a few miles down the road at a stoplight the tach dropped down to nil and the headlights went dim then the idle picked back up. Whenever I "coast" or don't keep my foot down on the accelerator it acts funny and seems to shift different too. Any ideas other than bad gas? The tank is below 1/4 so I will be putting more gas in by Saturday but definitely concerned with the sudden change in operation.

 

[Turdle]

If you do think it is bad fuel, burn out as much of it as you can before re filling.

 

[jaydez]

How many miles ago was the fuel filter replaced? The fuel system cleaner may have knocked some gunk in there loose and it got downstream and didn't burn right.

 

[4.6EXPLORERFAN]

So I finally got a chance to look under the hood and my oil filler cap was gone. I'm guessing that is the root of the problem and not the gas. So my problem then becomes the fact that I've tried several different "correct" oil caps from auto part stores and none of them worked! Going to have to post a new thread asking for pics.