Shuddering/losing power up hills 1994 Camry 4 cyl LE

This started a few weeks ago after getting maybe six gallons of gas at Costco on a low tank. After driving ten miles of so, it started shuttering when going up a hill. It was losing power. It would be fine, then the engine seemed to shudder like it was misfiring. I called Costco the next day and they said no one reported any problems.

Since then, it keeps happening. Not when I first start driving, but after being on the road maybe ten or twelve miles. Now, I do seem to notice it on bigger hills (out near Issaquah heading east on I-90, just past 405, or when driving up Cougar Mountain.)

It's getting worse each time. It's struggling now going up the big hills, and then the tachometer seems to go higher into the 3000s and it seems to downshift. It's the shuddering, "misfiring" that has me concerned. Twenty years ago, I experienced something similar in a 1980 Honda Civic (Honda 1500 DX, a 1.5 liter 4 cylinder! That's because I blew a cylinder, and the whole inside was coated with oil. I still managed to drive it another 400 miles as I tried to get back to school, adding a quart of oil every ten miles or so!)

Oil level on my Camry is fine, and the tranny fluid seems fine. It's got around 178,000 miles. I am due for an oil change. I had been low on oil a month or two ago (I think the Firestone stripped the oil pan bolt or something, so it seems to be losing oil, such that I had to add around two quarts a month or so ago. I added another 3/4 quart of oil last week.)

So...take it to Firestone? Is it as simple as a tank of Techron from Chevron to clean anything out? Some other fuel additive? Anyone else ever have this happen?

Thanks in advance!

Many things can cause this, usually plugs/wires, dirty injectors, failing o2 sensor clogged fuel filter, all these issues need to be checked out.

Sounds like you're getting oil leaking into one or more cylinders. Pull the spark plugs and check for oil fouling. If true, then it's probably time for new valve stem seals. The fouled plugs will result in the stumbling and missing. Do not drive this way for too long as the resulting rich exhaust will cook the catalytic converter and cause it to melt internally, which causes a restriction in the exhaust flow.

As a side, if you have changed the spark plug wires recently, check to see if they are arcing to the plug tube. Certain designs of Bosch wires are prone to this and can also result in the progressively worsening stumbling and performance and the same aforementioned cat damage.

Look underneath and see if there is oil coming from the plug seal...you should have fresh drops of oil directly underneath as well. If they did strip it or not put it in correctly, then they are liable for the repairs. Hopefully, there is no warranty on the workmanship. Take it back and have them fix the plug leak.

Hope this helps!