1996 Dodge Avenger PO300,302,304,306 Rnadom Multiple cylind

Hi guys here goes. Ok Girlfriends car (1996 Dodge Avenger ES V6) would nt pass inspection, so I came in and started looking for causes. I got engine codes PO300, 302, 304, 306, and one for an O2 sensor, replaced the O2 sensor no problem. Then I replaced the fuel filter, air filter, spark plugs, spark plug wires, rotor cap and button, plenium gasket, valve cover gaskets, tube seal gaskets, then I flushed the fuel injectors, then I ran sea foam. And still I have the same random multiple engine misfire codes on cylinders 2, 4, and 6. I feel a silght random misfire at idle, and when you put the car in gear the car starts to feel like its under a load and idles at the right RPMs but it shudders a little and you can still feel the misfire, however when you take off it goes away and seems to smooth out, and randomly I will get the check engine light flashing at me instead of just staying on. Now I was leaning to replacing the computer, because frankly I am out of ideas, so any help would be great.