Hi Scotty. I have a 1999 Lexus ES300 with 190k miles. My car runs great and very smooth, although it sometimes hesitates slightly at lower speeds (or maybe it's a slight transmission slip at low speeds sometimes, I'm not sure). I've driven up steep hills twice this year and have noticed my car really struggles up hills and everyone on the road passes me. For example, my car will stick at around 40-60 depending on the steepness, while other cars will be going 60-80 up the same hill. There doesn't seem to be anything wrong (no strange sounds, overheating, etc) aside from the struggle to get up. On flat roads and low incline hills my car runs great and achieves 80+mph very easily. Any thoughts?

More info on car:

  • A P0420 code comes on once every 1,000 - 2,000 miles. I simply clear it and move on. I think it started about 20k miles ago.
  • No other codes from OBD2 scanner. Fuel trims are perfect.
  • Transmission has had its fluid drain/filled every 15k miles since it was new.
  • Original fuel pump still (can they get sluggish when old without tripping codes?)
  • Fuel filter is 40k miles old.
  • Original heated oxygen sensor, but the A/Fs were changed 35k miles ago.
Comments (1)
No. 1-1
Scotty Kilmer
Scotty Kilmer


change the fuel filter and change the pump if that doesn't fix it

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