Only really started today, on way home so I'm fishing for advice. Have had a SLIGHT misfire (only missing once or twice), but VERY occasional, over last few weeks. However today, on way home got much worse. At first thought misfire, with plugs / leads etc, and was planning to start pulling plugs when I got home. Then the flashing to max temp thing happened, and the cruise conrol light has also come on. This looks much less like plugs etc, though have some wory about the catalyst, as, with running poorly, mis-fuels, and had a bad cat smell; not cheap!

Bought used 2000 Mercury Grand Marquis 58000 miles, shortly after purchase, the digital heat gauge will suddenly go to the top, chime and then go back to normal. At this time the car usually dies while going down the road but can be re-started and so far has always started back up. Went to a FORD dealer who said it looked like the PCM needed replaced which they replaced UNDER WARRANTY, but guess what... the problem remains and dealer now won't return any calls... So now I get the dealer where car was purchased (as is) and they look at car, they don't want to point any fingers but the PCM has not been replaced and they think it is coil #1 and coil #5 and a couple of spark plugs at a cost of $300, but guess what..... problem still remains... so what should I try next? Will Ford Motor Company be of any help on this?