"I have 95 contour,4 cylinder. When I turn a/c on I get a noise. I have been told this could be serpentine belt.."
What noise is it? When the A/c is on, it does cause a noise. Is it squeeling? Then yes, maybe it is the belt.
"When I press brake and car is in drive and almost stationary I get what appears to be vibration of the engine as it appears to be struggling (fine once I drive a bit faster)."
Probably broken engine/tranny mount.
"I was thinking replacing spark plugs."
This could help with vibrations too if the spark plugs have not been changed for 60k miles or so.
"Anyone know the spark plug gap"
0.050 inch for 4 cylinder.
"what size socket I would need?"
Get spark plug socket from Autozone or Advance.
