Hi. i have a 98 dodge dakota 3.9l. before my customer brought it to me, he had a cylinder 2 misfire, so after a tune up, new injector, various other parts swapping, still had a cylinder 2 misfire. vehicle was this way when he bought it. it has a rough idle but runs great off of idle and down the road unless the rpms come down like in final drive, in gear at a light you can feel it worse. So he pulled the heads, and replaced both with new (machine shop said both heads in both front and rear banks where cracked between the valves) which i have seen before. so the customer bought the new heads, replaced lower intake pan gasket and all head set gaskets and reassembled. Thinking the cracked heads where the smoking gun. Well, not the case. after numerous attepts by him he still had the cylinder 2 misfire at idle, also causing a CEL. A week ago brought it to me, i started from scratch, cylinder 2 misfire code, on my (snap on versus scanner) at idle can steadily watch cylinder 2 rack up misfires, anything off idle it will stop. so i swaped injectors around, same, took his autolight plugs out and installed champions, same, swapped plugs wires, same, did a compression check on cylinder 2, 130psi, seemed ok. put my versus lab scope on each injector and watched the waveforms, idling and throttle snap, all cylinders showed the same. so then i pulled the fuel rail off and inspected for rust or debris, none found, swapped injectors around again, same. ive sprayed the intake down with spray lube and brake
cleaner, same, while i had the fuel rail off, disconnected ignition cranked of and all injectors sprayed well. i even pulled the passenger valve cover off, swapped number 2 and number 4 rockers and push rods, same, watched for full travel, looked good to the eye but i had no dial indicator. what am i missing, or where to go now, im more than happy to start fresh again now that they brought it back today. i only have it for the day of thursday as they use it for a mail route. any advice would be greatly appriciated.