escort sticking valve?

My 97 Ford Escort has an intermittent problem. Sometimes when I start it it runs really rough, like its running on three cylinders. It usually smooths out after a minute or so. If I stop the engine and then start it soon after while it's still hot then it invariably happens. sometimes it will start to run poorly while I am driving and then go away for no apparent reason. I have replaced all filters, coil, plug wires, plugs, pcv valve to no avail.
Maybe it's a sticky valve? How can I diagnose this? Is there some product that will deglaze the inside of the engine and help this?

Johann

Welcome fonorono, I hope you will enjoy the forum Are you using a vacuum gauge?

I'm not feeling sticky valve here...

Three things it could be, compression, fuel, or spark. You can eliminate compression by using a compression tester. The numbers should be close, 10psi +/- of each other. That would be my first guess from what you're discribing. Low compression in one cylinder won't allow combustion to happen well until engine temp and/or velocity is up. If it is a stuck valve, you will have almost no compression in the cylinder. I would think it was the rings or valve seats.

If it passes that one, pull one spark plug wire at a time while running and see if one of them dosn't make that much difference if on or off. Keep your other hand in your back pocket to avoid getting shocked. If one dosn't make that much difference, that one is your "bad" hole.

When you replaced the spark plugs, did any of the plugs not match the other ones as far as color? This is also a good indication of the "bad hole"

Fuel would be my second guess, clogged fuel injector. You can check this by swapping an injector from a "good" to a "bad" hole, and see if the problem moves.

Lastly, spark, it sound like you have already replaced most of the components, but sometimes you can get brand new bad components. Check your grounds, battery cables, and that your charging system is functioning well. Sometimes those basic things are overlooked.

A few other things could be EGR valve, clogged EGR passage ways,
vacuum leaks, carbon build up on intake...

If after all that you are still convinced it's a sticky valve, you could physically verify it by taking the valve cover and watching the valves move as you hand crank the engine over. To deglaze the inside of your engine, I would recomment Seafoam or B-12 Chemtool. Add it to the engine oil while **COLD**, run for recommended time (I believe two minutes), then immediatly drain the oil.

try a cheap and dirty fix use f type transmission fluid rev up engine apply or spray to air intake.if noise goes away theirs exhaust carbon buildup between valve stem and valve guide.i had a 302 v8 that would do this once and while it would fix till next plug fouled then it would start over.this saves alot of work tearing engine down.only other thing it could be is a a burnt valve.compression test will confirm this. good luck