Muffler exploded. Fuel leaking into exhaust? '99 i-30

[freet]

On the highway, the car started to bog down...I accelerated and KABOOM!!! My muffler completely exploded. At the muffler shop they said it was most likely due to a fuel leak into the exhaust. Is this something that has happened to any of you? What causes my fuel to leak into my muffler? How do I go about solving this one? Is it a very expensive fix? They said it will happen again if not fixed. Thanks for your help...great forum*

[MinisterofDOOM]

Things that come to mind:

Car could be running richMight have a bad spark plug that is allowing unburnt fuel into the exhaustFuel injector may be sticking

Unfortunately if you had enough fuel in your muffler to ignite, your catalytic converters are almost guaranteed to be shot as well.

Has the car been running okay? Any of the above 3 problems would cause the car to run rough or get crappy gas milage.

[freet]

Thank you for the advise...I will ask the mech. to look into those specific areas. The car seems to have been "softly" backfiring but more like "chugging"..not all the time...like only now and then and not for long...doesn't seem to matter if it's raining or cold...only happens for a few seconds every other day type thing...but it does seem to be when the car is under a bit of "pressure"...I mean like going up a hill...applying the accelerator..not much...just slightly and again, only once in a while...????

[NutriaforBreakfast]

Check the EGR valve. It might be stuck closed.

[freet]

Thanks...I will mention that as well...I appreciate it!

[freet]

One other thing... Also, meant to mention that my idle seems to be a bit high...especially when cold...at about 1700-2000 rpm?....could that be any of the cause or added factor regarding this? Sorry if that is a sort of "brain-dead" question. I appreciate the help.