Horrible sound

I got a 1997 pontiac sunfire a month ago and love(d) it until today. I was driving on a highway today just fine. Not running hard, or carelessly, until a traffic jam. I started to slow down and noticed a horrible knocking under the hood. I tried to give it some gas and I could only get ten miles an hour at 5600 rpms. My temp. guage never moved, my oil light didn't come on, or anything. I had it towed home until I can get the money for the repair. but does anyone have an idea? Please Help.

Check the fuel pressure, may be very lean and knocking cuz of that...

possibly spun rod bearing, does it by chance have the 2.4? That happened on my Grand Am, only I was beating the hell out of it at the time :)

how do I check the fuel pressure? and no it's a 2.2