I had similar issues with my 97 with the 5.4L and the light eventually started flashing too. I sure sign it had gotten worse, lol. I changed 6 of my 8 plugs because I just could get to the back two on one side and had to change one of the coil packs as well. That took care of the flashing light issue, but mine still stays on all the time. Take it to Advance Auto or Auto Zone and let them run the codes for you. With the codes, you tell what is the malfunction and hopefully correct it. Ask a lot of questions and the guys will surely help you out.