I replaced the coolant sensor and still my car every so often loses power when going up hill and then grabs it again. She feels like she wants to stall then changes her mind and keeps going. It's like a sputter every so often. Any more ideas? Thank You!

Maybe fuel pump is intermittently failing for a second at a time, thus momentarily starving the engine of fuel.

The way to test this to either hook up an odbII scanner with real time data display (actually I'm not sure if it the PCM monitors fuel pressure ) OR hook up a fuel pressure gauge to the fuel line's schrader test port located under the hood and measure it by viewing the gauge as you drive the car. You seem to know how to get it to act up under stress -- so go do so and watch that fuel pressure needle on the gauge when things act up. It may drop to 0 momentarily, then right back to normal.

If so, you'll likely need a new fuel pump.

You can do a free loan a tool at autozone or similar or by an inexpensive one to have and to hold.

This is a total educated GUESS. But one that is sorta consistent with your symptoms.

And the only thing it costs to check is time.

Thank you!

I have had a fuel pump go bad in a pontiac I owned one time and it was making wheezing sounds. You think even though I hear no wheezing sounds the fuel pump could be a possibility?

Do you think maybe fuel filter could be issue too?

Thanks for your time!

Yes---That's why I suggested it. And s car fuel pumps are electric, so i doubt you'll be hearing any wheezing.

Put another way, "a Pontiac is a Saturn not"

Could be -- how many miles are on it? Could be restricting fuel flow at high loads but from the way you describe your loss of power, it is kinda momentary.

Can't hurt to change the fuel filter FIRST. Then we'll see what happens

ok will change fuel filter first thank you!

Hi so I've changed the fuel filter now and my car runs much better but it still has issues going up hill. Meaning it jerks a bit and loses power ever so often. Not as bad as it was, so it seems I am fixing the issue but there is still an issue.

The code I got was PO 137 what do you think? Thanks

thats a o2 sensor code . the sensor "after" the cat convertor . that in itself doesnt seem like it would cause your problem ,but if the cat is starting to clog ,well then.....

The rear O2 sensor primarily determines if the cat is working, however it sets the long term fuel trim. This is the course fuel trim. The front sensor fine tunes the the fuel trim, but if the rear isn't working, the front sensor has to work harder. They can also give false codes for the cat leading to unnecessary but expensive repairs. I'd change it.

Ok thanks I'll change the rear O2 sensor. What do you think about the fuel pump? Because the lose of power happens when I need more fuel, as in when I am going up hill.

Thank you

Its a valid conclusion. There are fuel pump pressure checks but I don't know of a flow test other than filling a bucket. Not sure anyone does that test anymore.