I'm currently getting 11/14 MPG. I have 258,000 miles on it, and feel lucky that it's running at all. Got it a couple months ago, and found it had no cat on it, after putting one on, It's running worse than ever, any suggestions?

 

Can you be a bit more specific? What are the symptoms it's showing?

 

NO power (even less than expected from a v6) even the slightest hills and I can't get it to speed (35 mph) without mashing the pedal to the floor. Timing is off, but is the best running point there is. Harder to start since cat, used to be able to turn key and start, now have to hold pedal down, and keep it there until it smooths out.

 

There should be a "Set timing" connector, that has to be disconnected when you set timing. I think it is on the passenger side, by the a/c box, should be a tan wire, with a black stripe, single wire, inline connector. (to the best of my knowledge, your results may vary....) Disconnect it, start the engine, set the timing. Shut off engine, reconnect, and see if it runs any better. (you will prolly have to clear codes after setting the timing.)

Check fuel pressure. Although, this may be fun on a tbi, don't think it has the schrader valve.....

Does it smoke? Use a lotta oil? Might be low compression.

When is the last time it had a tune up?

 

No smoke...except normal cold weather steam. Doesn't use any oil. Put new plugs, wires, cap, and rotor.
How do you clear codes?
I will try to find the Timing wire next clear day.
Mind you, I got this used about 3 months ago, so I don't know it's history b4 that, But seems to be fairly well maintained.