i know there are alot of threads our there like this already but i need help i think its getting worse. so far ive changed plugs wires O2 sensor and hasnt helped much. i dont wanna just keep guessing and buying parts. no leaks fuel leaks that i can smell. i do have vacuum lines that arent hooked up but i have them all plugged off. how do you test the dist. cap? im gettin like 9.5 mpg city and if im lucky 16 hwy. also how do i check the EGR?? its a 92 3.1 camaro and no codes or engine lights

 

anybody???? any suggestions are appreciated

 

Check injectors for leakdown?

 

im waiting for the parts store to get it back, they have it rented out right now. but i heard that if there is pressure in the gas tank when you take off the cap you should be good or am i wrong on that??? like when you fill up and first take off the cap it hisses??