Q&A

Thank you Raiderron. I was thinking the same thing but I don't have a lot to go on... Throw a 73 bug my way and I will sound like a master mechanic but I guess I am showing my true colors here...

This could be something as simple as a loose connection. Has any work been done recently in the area of the fuel injection system? Other work being done could have required parts removal for access and may have then caused a loose connection that is causing this. When these codes appear there is always a step by step procedure for the diagnosis of the code and somewhere in those steps the problem is typically found. One of the steps is always check for loose connections and tests to see if pressures are what they should be under different load conditions.

Found online:
I have the P1580 code as well.

I cleaned out the throttle body and was still getting a rough idle. So i went under the hood with the car running and noticed a vacuum leak on the hose attached to the air box which has apparently fell down on to the belt at some point.

I fixed that and could still here some sort of hissing. I noticed the crankcase vent hose was completely severed in 3 separate places.

Now of course I need to replace this, but in the mean time I'm curious if this hose could be having any effect with the p1580 code, and the rough idle? I'm guessing this could be throwing off the vacuum circuit.

More from online:

check the vacuum line that runs from the intake manifold to the brake booster

I got this code twice on 2 different ABAs and on both occasions the throttle body was fine and it was that stupid cracked vacuum tube

It appears that vacuum leaks are likely the culprit for your problems. Good luck.