I have a 2004 Volvo XC90 2.5T. Last night I changed the spec plugs as I had a P0303 and P0304 code. The car still had the original plugs after 200,000 miles so I assumed it was that. I took out all plugs with ease except cylinder 4. That one broke in half. I ended up using PB BLASTER to loosen the other half of the plug and got it out. After putting everything back, the car started up great and the CEL was off. This morning I was driving my car and the CEL came back on and started flashing. The car then stalls out. It cranks but will not accelerate as it does within seconds. Could this be because of me putting the plugs in incorrectly or even putting the wrong coil in a cylinder? There was a bit of oil under the valve cover as well in case that has something to do with it. It wasn’t in the cylinder walls but was in the holes around the plugs.