Cars not running right....help??

[Wishes527]

Well I was driving home yesterday from a weekend getaway, and stopped in to refuel....
Before that my car seemed to be running just fine...as soon as I got gas I noticed a horrible pinging from my car, in fact I would have to downshift to 4th on inclines just to get it to not sound so bad.....
Well i assumed, bad gas ???
However this morning I got up and went out to start the car, it started just fine until the choke kicked off. then it sounded horrible, like it was misfiring, in fact it backfired a couple times...you had to pretty well floor it to keep it running. I seen black smoke so I went around and sure enough, a nice black sooty spot below the tailpipe.....
I checked the spark plug wires, thinking maybe one got melted on the manifold or something......they seem fine...
What should I look for??? I'm really not a mechanic chicka so I'm at a bit of a loss....but I don't even want to move it from the driveway til I figure out whats going on with it.
This car is an 02 V6....40,000 miles on it.
Just had an oil change.....oh, I took a look and the oil cap was loose...not sure if that means anything ????
Any help would be awesome!
Thanks,
Stacey

 

[Adverse2Change]

Check your oil level. Let us know if its ok.

 

[Wishes527]

I just checked the oil level...it reads above max .....what does that mean?

I've been asking around....someone told me it sounds like I put diesel in it by mistake? Could this do it? I know I read the pump but....makes me wonder, it was an older gas station.....

 

[Adverse2Change]

If you think that is what you did, you can siphon out as much of the fuel as you can and refill the tank with regular gas. It may smoke like you said until it is all worked out of the system.