95 Sonata Performance Problem / Missing Vacuum Line?

[javierrpaiva]

Hello people, lately I'm having performance troubles with my 95 Sonata GLS (2.0 L). The engine is very shaky at idle (revs drop a lot...) and in general the fuel consumption and performance aren't in a good shape. Worth to mention I have an aftermarket LPG kit installed (the dual system, lets me run either on gasoline or LPG), however the problems I'm mentioning occur running on either fuels. Any clues on what should I check before just raising the idle speed? Perhaps ignition timing?

Some extra info on the car: I have already replaced all filters and checked the spark plugs, they are in good condition. I have a tranny fluid leak (AT), when I had it checked they told me the leak was too near the gearbox so they would need to take it out to repair it, since I didn't had the time nor the money then, I have to put in extra transmision fluid now and then until I have that leak fixed, which should be by the end of this month (mmm.... now that I remember, haven't put extra tranny fluid in a while, the gearbox must be quite dry... should buy some today). Oh, also I have found that near the idle screw (what's that piece called in English? throtle body?), there are three plugs for vacuum lines (I think they are for that). I have realized that only two lines are plugged in, the other plug is just there sitting alone (I have looked for that unplugged line but didn't find it). My meantime solution was to put a cap in the plug to seal it and prevent it sucks air.
Does anyone know what are those plugs for? Could the missing hose there, be a reason for my performance trouble? Thanks for reading this huuuuge post, sorry, I tend to talk too much!