I am not sure, but, if you do a vacuum check, you will find the Crankcase Ventilation Filter Valve may need changed.
I had a similiar situation with my 1989 Ford Escort, 1.9 L. Check engine light was driving me cerazie. I pretty will changed anything that had to do with the computerizied system.
Even though the engine had no crankcase vent. valve, I found a hole in the vacuum hose that sent the signal between the cranckase and the intake manifold. Changed the hose $$$ and the light never came on again. A month later, some older gentleman did me a favor by rear-ending me and pushed the car into a Chevy pickup with a large trailer hitch that destroyed the entire front end, engine and all. Made some "legal money" from the total loss of the automobile.
Moral to the story.....check the crankcase bvent system from your diagosis. With a bad vent valve, the engine will not idel worth a darn.