2001 Taurus SEL Check Engine Light

Hi all,
I own a 2001 Taurus SEL (w/3.0L 24V DOHC) with 66,000 miles.
In July of 2005, the check engine light went on. The check engine light
would also blink when idling in traffic for short periods. The engine felt like it was going to stall when the check engine light was blinking. I took it to dealer #1 and they told me that the compression in cylinder #4 was low and that they would have to take apart the engine and the cost would be at least $1,500 just to find out what is wrong. So I then went to dealer #2 (where I originally bought the car new) and had them look at the car without telling them what I had found out at dealer #1. Dealer #2 replaced the spark plug and said it was fixed. I drove from the dealer about one mile and the check engine light came on again so I drove right back to the dealer. They then replace the wire harness and apparently this fixed the problem. They also said the compression was fine.
Well, the car ran fine for a year, but the check engine light is on again and it blinks when idling for short periods. So, I took it to dealer #2 and they said the compression is low on cylinder #4 and that the Exhaust Valve is sticking or burnt and it needs head work. They would need the car for three days and it would cost well over $1,000.
Anyone know what is going on here and what I should do?
Is it dangerous to drive the car with the check engine light on or blinking?
Thanks in advance for all your help.
- tmarin7
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Blinking indicates significant misfire. Don't know about dangerous (except to our lungs, due to pollution), but the unburnt fuel will destroy the catalytic converter and add another $1000 or so to the cost.

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[This followup was posted to alt.autos.ford and a copy was sent to the cited author.]
snipped-for-privacy@comcast.net says...

If it is a valve problem, the spark plug is fouling, although it could also be the other way around. You can probably see about cleaning and/or replacing it often as a temporary measure, but as others posted, it may damage the catalytic converter over time. You may also want to have somebody double-check both the wires and the coilpack to make certain you have good spark, as it's possible ignition problems have fouled the valve. Adding a gas additive that cleans valves may or may not help, although I tend to believe not.
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tmarin7 wrote:

< SNIP >

Any answers you get here can only be pure speculation until you get the codes read (like at an autozone) and post the numbers here... P0301, P0302, ... P0306... etc.
And those numbers are just a starting point. With any luck you just need new coil-on-plugs, but worst case your compression or fuel injection is bad. Get the codes.
And do not drive the car with the engine light blinking or you will wind up doing more damage.
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