All,

This is my first post but have been "listening" for years and have used many of you all's advice. My 89 (218K miles on 4ZE1 engine) very quickly developed rough running and idling problems last week. In chronological order here are the symptoms and efforts thus far.
1) Engine would start fine but started idling roughly and slowly until warm.
2) Suddenly, and at freeway speeds the engine would not hold power under load; max speed became about 45 mph and engine seemed to be running on 2 or 3 cylinders.
3) I suspected vacuum leak so checked and replaced every vacuum hose visible with no change. Engine still runs rough although will run above about 1200 rpm after warm.
4) I verified spark and compression on all 4 cylinders although the 2 and 3 cylinders are weaker than 1 and 4.
5) I checked and re-set all 8 valves to spec. 2 were a little tight but it made no difference.
6) I verified operaton of the fuel pressure regulator per shop manual
7) I inspected the throttle body for obstructions, etc. and found nothing
8) I ran out of ideas and am writing this letter

I know there are a couple of vacuum lines underneath the air chamber and I verifiied their connection with a mirror but am wondering if there are other areas any of you know of that can typically cause such a leak or these same symptons?

Thanks for any help......Randy