Engine Mechanical problem
1999 Isuzu Trooper 6 cyl Four Wheel Drive Automatic 130000 miles
check engine light came on on start up, one mile down the road it started running as if a cylinder was missing. I pulled into autozone and had them read the trouble codes. It said missfire in cylinder number 6. I changed the plugs, they looked fine, new plugs did not fix it. I had the battery disconnected for about half an hour. Upon start up, the check engine light came back on after 20 seconds, then immediately began to flash, engine running rough the entire time. What's my next step?