On the highway the acceleration does not respond as it should. However When I drove it, everything was fine until I got to work and it began to rough idle. I changed the spark plugs (old one were full of carbon 5/6 of them) and changed the O2 sensors all 4 (Bosch sensors). I plugged the OBD-2 and during idle it goes from 800 RPM down to 350-480 rpm. My neighbor might suspect it is the distributor cap causing the issue.