I had a Dakota pickup built during that same era that would kick that alarm/code frequently.
It was usually a split/cracked rubber hose under the car. There are a bunch of them running the length of the car to and from the gas tank, charcoal canister, purge solenoid, etc.
They could be a pain to locate--I didn't have a smoke machine.
Seemed to me there was an issue with the hoses they were using at that time--very poor quality and always cracking.
The lines running under the car usually are not rubber, they are usually a hard plastic, the only rubber is connections between the hoses and any right angles .
Check the fuel fill pipe, if it is exposed enough to road mist/debris while in motion the tube will probably be corroded pretty bad, even if you live outside the rust belt ... case in point my new to me 1998 Ram 2500 that I got out of Arkansas , there all it's life and only 172k miles , the filler pipe is corroded as bad as my 2000 Ram 2500 that's spent all it's life in New England.
