I have a 93 legacy with 230,000 miles, and until recently it ran great. It than began having some issues, which I will try my best to explain, and I will tell what I have done to correct it.
When accelerating up a hill (merging onto a 65 mph highway from a dead stop) I would wind it up a bit to get to the speed of traffic. Watching my tachometer, I'd hit about 4500 RPM in second and 4000 in third. As I reached the top of the hill, there is a "sputter" or "miss" and the engine runs very rough, and loses power, almost to the point of stalling. Several times I had to pull over and idle it for a few minutes to get it to run enough to get to work.
Since this started, my performance has diminshed. I have lost 3-5 mpg, and can no longer hold 4th and 5th gear on inclines like it did just a few thousand miles ago. When on a mild incline, in 5th gear, anything below 40 mph is difficult for the car to hold, and acceleration is out of the question. Everything requires a gear-down when it never did before.
So, since this is my "beater", I set out to correct it. This is what I have done:
1. New plugs and wires (didn't help)
2. New fuel filter (no help either)
3. New ECM (Yawn, no difference)
4. New O2 sensor (keep reading......
When I changed the O2 sensor, it ran great for about a week. Then the same old stuff started again. I thought maybe it was a faulty sensor, so I traded it for a new one. Nothing changed.
Does anyone have any ideas? A bullet through the engine block is a tempting option, but not practical.
I have no engine codes that I know of (engine lights does not stay on after starting).
Thanks in advance for your advice,