Odd Sound

[flat4]

I was on the way to work this morning, and about 5 min from the office, the car started running really, REALLY poorly.  It lost power in a big way.  Its a 75 Super Beetle, running stock FI.  I limped it into the parking lot, and opened the hood to find that one of the fuel lines to the injectors was leaking.  No big deal.  I fixed the line on my lunch break, and when the car was started, it took a few tries to get the engine to start idling properly.  No big deal, except for the fact that when I opened the throttle a ways, there was a really strange knocking coming from what sounded like inside the case.  It was an inconsistent knock, but not a good sound.  At idle, everything appears normal.  Under any type of throttle position, lets say 2000 rpm or more, well that's a different story.  It runs ok, but I opted for stopping after only a km or two and I'll be towing it home for fear that this is terminal, and I'm hoping to salvage what I can.   This all seems kind of strange to me, as yesterday I drove it for an hour and a half at highway speeds without any issues.  It was running just fine yesterday.  Today, different story after 10 min of driving.  Could this be rod knock?  Ideas?  

[BUSDADDY]

HMMMMmmm....
Without hearing the noise it's impossible to tell for sure. An underfed injector may cause a lean cylinder that could burn a piston in an hour and a half of highway driving. Once you fixed the leak and it started working normally it could make an ugly noise.

Have a good look around and see if something major has come loose first, what made the injector line fail? did it die of old age or was part of the engine moving around to break it? like head nuts which cause loose barrels which knock too. Look for a big oil leak underneath where the barrels meet the case.

Run the engine at idle and stall it with the key on and see how many seconds it takes for the oil light to come on, if it comes on instantly suspect your bottom end, if it takes a few seconds look elsewhere.

Do a compression test. Compare the spark plugs and don't mix em up, they will tell you which one is bad.

Try turning the crank pulley back and forth and see if you get a similar sound.

Look around underneath for other loose things (mufflers, etc.) that could make the sound.

Drain the oil and look in the screen.

It could have something minor thats loose that makes the noise and crap in the injectors from the hose fix that makes it run bad.
Best of luck.