impreza 94 when first starts -bearly runs, but when warms up its just fine

[terenty]

I wish this car had an obd2 hookup, check engine light is on - I have no idea why the car started to be that way. Please give me direction where to look for a problem. Also just recently I had it sitting for number of days and then when opening gas tank lid I heard presurized vapors come out- it probably should be vented? right? are theese problems connected?