1999 Ford Escort SE

114,000 Miles on it.

It was idling/starting rough. it was very sluggish until about 30 MPH

I replaced the spark plugs and it ran great for 3 days.

Now its WORSE, and my check engine light started flashing. Any ideas?

We want to help out, but first we need the code of the Check Engine Light. If you take it to one of the Auto Zones there in Columbus, they will hook up their code reader free of charge and let you know what the code is. Don't take it to the dealer for this or he'll charge you $85.00. After you get the code at AutoZone repost here with what they said you needed and we will take it from there. Dave

114,000 Miles on it.

It was idling/starting rough. it was very sluggish until about 30 MPH

I replaced the spark plugs and it ran great for 3 days.

Now its WORSE, and my check engine light started flashing. Any ideas?

check the condition of the plug wires sounds like an issue there. Do the night test run the car and look under in the dark and see if you see blue sparks. I'd guess the pllug wires need replace them also check your coil/pack.