Can you give me the actual "p-code" that was retrieved?
Ok. First- you didn't need to spend $99 for a diagnostic, most local "big chain" parts store (ie- Auto Zone) will read codes for Free. Sorry to be the bearer of bad news.
As for the problem- it would be a more accurate diagnosis with a "p-code" however, from what you are describing it sounds like you have an "EVAP System Leak Detected" (this is the emissions system). And, unfortunately, the best, XXXXX XXXXX way to find this leak is, in fact, to have the EVAP system "smoked". This is where a machine forces smoke through the system, and the "leak" will reveal itself with a stream of smoke. Most shops charge anywhere from $40 - $100 for this service, but, like I say, money well spent. Find the leak, fix the leak, and be done with it. You may want to shop around and see if you can get a better price that $99 to do the smoke test, as many local shops have a smoke machine these days to keep up with today's EVAP repairs.
Ok- yes, this helps. Actually, with this p-code, a "smoke" isn't going to help you at all. The most common fail item associated with this p-code is the EVAP Canister Purge Solenoid. Most of the times it's just the solenoid that fails (which is why a smoke test won't help- usually it doesnt "leak", it just fails.). Check all the electrical and vacuum lines to/from the solenoid for holes or disconnections. If no visual defects are found, suspect a faulty purge solenoid. The EVAP canister purge solenoid is located in the engine compartment. It is attached to a bracket located between the battery and the Power Distribution Center.
The p-code was 441 - evaporative emission control system incorrect purge flow - does that help?
Absolutely. If you see any vacuum lines with holes, or disconnected, fix the line as needed. Make sure the electrical plug is tight as well, and no signs on broken or rubbed through wires. Try to follow the vacuum lines from end to end, any little hole can cause this. If visual inspection is clean, more than likely this solenoid has failed.