Autozone has all sorts of info for repairs and maintenance.
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1b/c8/aa/0900823d801bc8aa.jsp
I am surprised that the mechanic refused to do the carb cleaner or propane gas test. Maybe they just do not want to deal with a Contour.
You should try it yourself. Pick up a $5 can of carb cleaner at Autozone or Advance and while car is idling, spray where gaskets are. Slowly moving from different areas. Throttle Body gasket, EGR gasket, air filter housing, Idle Air Control gasket, Upper Intake manifold gasket area, Lower Intake manifold gasket area, etc. The Autozone site will have pictures where this components are located. Good luck.
And don't forget to try all the suggestions (that you can manage) previously posted; IAC cleaning, etc.
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=trouble&Number=1197971&Forum=trouble&Words=iac%20clean&Match=Entire%20Phrase&Searchpage=0&Limit=25&Old=3months&Main=1197774&Search=true#Post1197971
