Thanks for your info. Today I drove my dual falcon to fix shake + misfire problem, steve tune up the gas system and charges only $30. A week ago, another mechanics charged me $200 for changing spark plug but still not slove problem. In addition, he quoted me 1999 camry $1000 to add a new LPG system or $700 for tested 2nd LPG tank seperately. So far, I am happy with his service. If one month later, the shake + misfire problem really gone, I will install LPG for my camry in his store.