2000 ls 3.0 5speed, highway acceleration.

[Cicerojonezz]

So just got my coils&plugs and both cats done and she's running a lot better now at low speeds/gears. However she's really struggling after 3rd gear, especially up slight inclines and definitely not getting power after 50-60mph.

I'm forced to downshift from 5th to 4th going up even the smallest inclines on highways or my speed will fall with the pedal floored. Even when I downshift she barely manages to maintain speed.

My pedal also seems really low to the floor, but my mechanic says I get full throttle so idk.

Fuel filter?
Air filter?
Fuel pump?

Anyone have something similar happen and got it fixed?

 

[milehighmikey]

Clogged catalytic converters could do something like that. Mine flies up hills with no effort, 5th gear accelerates uphill at any speed over 40 mph. 70 to 100 in maybe 10-15 seconds on flat ground.... with over 315K miles. Yours definitely has a problem. Also check brake temperatures after some normal driving. They should all be close to the same ability to burn your skin, none should be like shockingly hot and way out of line with the others.

 

[Cicerojonezz]

Clogged catalytic converters could do something like that. Mine flies up hills with no effort, 5th gear accelerates uphill at any speed over 40 mph. 70 to 100 in maybe 10-15 seconds on flat ground.... with over 315K miles. Yours definitely has a problem. Also check brake temperatures after some normal driving. They should all be close to the same ability to burn your skin, none should be like shockingly hot and way out of line with the others.

I have brand new converters so I don't see how they can be clogged with less than 50 miles on them. Also have brand new rotors calipers and brakes, new coils and plugs, all with less than 50 miles on them. Could the converters be clogged with less than 50 miles on them?

I'm thinking it can only be the fuel filter, fuel pump, air filter, pcm or a combination of them.

She's just really struggling to accelerate at higher speeds and really struggling with 3000rpm+. I'm not sure what else it can be at this point.

 

[04_Sport_LS]

No check engine light? No codes? Are you using dummy plugs where your O2 sensors are?

 

[Cicerojonezz]

No check engine light? No codes? Are you using dummy plugs where your O2 sensors are?

Yeah there's codes.

P0175 - too rich bank 2
P1131 - lack of HO2S11 Switches - Sensor indicates lean
P0171 too lean bank 1
P0303 - cylinder 3 misfire

I have brand new coils, plugs, 02 sensors, and cats.
I don't know where to go from here.

Really dont want to burn out my new cats lol.

 

[milehighmikey]

Did you check your PCV rubber hose elbow under the intake? Almost sounds like that problem. They turn to goo and just open up to the atmosphere. Short of taking all of that stuff back off as had to be done when you changed coils and plugs, you could try a smoke test of the pcv system if you can access a smoke tester.