75 1.8 suddenly have a lot of backfiring on deceleration/leting off the gas. Seems like a slight loss of power as well. ??

Look for an exhaust leak.
Try the shop vacuum pressurization technique.
It works pretty good.

So, I just found a hole in the exhaust. It's in a foot long section of the exhaust pipe just prior to the muffler. Could that cause backfiring? The hole is about an inch and a half long and a quarter inch wide.

BIG time. And can even fume you out of the car.

I'm sure you'll have that fixed and be ready to run with the big dogs saturday morning, right?

Dude, I'm registered, where can I find that piece of the exaust before saturday???

Looks like its the "catalytic test pipe" section for 75/76, it's totaly shot. I can poke my finger through it. The rest of the exhaust is fairly new, just this one piece is totally rusted. Anyone in Sacramento area have one of these? I wanna run with the dogs in Sonoma saturday.

If it's a "test pipe" you should be able to remove it and have it duplicated by a local muffler shop.

Cool, I'll try tomorrow.