Dave Merrick wrote:
I'm having the EXACT same problem.
At startup, the car would puff out black smoke till it got warmed up. I took it to the mechanic for a tune-up and some other work (New water pump, etc...) It ran flawlessly for about 2 days. Then the black smoke came back. A friend of mine smelled it and said "Yup, that's gas" Now I also have a chugging engine. I tried the screwdriver trick to no avail.

One thing I did notice is that when I got it back the vacuum hose was disconnected from the wiper pump and left hanging I hooked it back up and the engine started to chug. So I took it off and it hasn't stopped chugging since; with or without the hose attached.

What now?