at 45 mph. it would run real rough. i found i could disconnect the vacum line off of the egr valve and it would run fine. so i replaced the egr valve. it still ran rough. so i disconnected the vacum line off of the egr valve again. it ran fine like this. so i decided it must be the egr solinoid. i got one out of a wrecking yard. it fixed the problem for a little while. now it's running rough again at 45 mph. and 65 mph. nowhere near as bad as before. also i have found that disconnecting the vacum line now doesn't seem to help. it only blows black smoke when the engine is first started and i accelarate onto the freeway for example. the check engine light comes on when i turn the key on and goes off when i start engine. any ideas? thanks keith