Yeah I am having the exact same problem only mine is an 88 and I have gone a little more extensive in my replacement list. I have yet to change out the oxygen sensor and that could be the culprit. I do know what you mean about the frustration thing though manno! Anyways if I figure it out I will let ya know. I'm gonna pull the codes tommorow. Darn 2.9's are one hardcore engine though aint they! LOL.