I would not think a problem with the EGR control would cause misfiring or erratic running - unless something else was marginal. How many miles are on the spark plugs, and how many years old are the ignition wires? The plugs and wires and inexpensive, not too hard to replace, and will not last forever.
Along with changing the spark plugs you look at the old ones. Good plugs should be a very light brown in color. If there is a lot of misfiring when the engine is cold, it will make the plugs darker.
I am assuming your car is an automatic transmission. I wonder if the jerking could be related to the transmission shifting, or trying to. Have you checked the transmission fluid recently? It needs to be done with the engine warmed up and idling. I would say weird things will happen if the transmission fluid is low - really low.
....But...Yours is a 3rd generation Escort, and mine are 2nd generation. Slightly different engine controls.