fuel related problem with 91 190 e
 

I have a 190 e with a problem rough running hard starting, started acting up all of a sudden, did a compression check all 4 cyl are 120-150 psi, have new cap and rotor and plugs, wires are about 6 months old, when I pull the # 1 or # 3 plug wire off while, motor is running no difference still runs the same. I thinking perhaps fuel related the injectors are most likely the same age of the car. I am thinking that this is a commom problem and some one might have a idea of which way to go next?