Rough Idle, PO303 Code

[rkhodges21]

Well the hits keep coming. On my way to the parts house to pick up the parts, tools and fluids for the work I'm planning for the UIM/ LIM gasket job and the trans cooler and shift kit install and my car starts running really rough at idle. I make it to the store and they pull a PO303 Cylinder 3 misfire code. So I pick up a new set of plugs and wires and change out number 3. No better. Get a new coil and install and it still doesn't fix it. My dad's shop is just a mile down the road so I am able to get it over there, and his mechanic takes a look at it with me. I will add that the car runs great if I give it gas , but when it idles it is super rough and sputters when revving up for a second. So we pull the #3 plug again and it is already wet with what he believes is coolant, but it looked dark brown like oil to me. No sign of chocolate milkiness to it either. He checks the spark and it is very weak orange. We test a fresh plug on the 3 wire and it is strong blue. We pull the #6 plug to test and it is much cleaner and still has a stronger blue spark even to be an old plug.

Could blown intake gaskets really be causing this issue, or should I be looking for another culprit?

[nos4blood70]

Could be a lower intake gasket failure over the intake port in the head, letting oil mixture into the cylinder, rather than coolant into the oil passages. I might be all wrong though.

Another thing to do would be to swap an injector and see if the code follows the #3 injector.

[rkhodges21]

Could be a lower intake gasket failure over the intake port in the head, letting oil mixture into the cylinder, rather than coolant into the oil passages. I might be all wrong though.

Another thing to do would be to swap an injector and see if the code follows the #3 injector.

Thanks! I will certainly try swapping the injector to see what the car does. I am also thinking of doing a compression test for peace of mind. I was also thinking of checking the valve seals as well.