92ES5sp

^The front one is easy, but for the rear I think the passenger seat has to be removed to access the wire harness.

If theyve never been changed, the original O2 sensors with 177K on a 92 are probably no good. Usually 100K is the norm. A couple of things you can check are vacuum lines and the air intake hose for cracks. If the engine runs halfway decent as it is, you can probably get away with doing both O2s and a full tune up with plugs, wires, cap & rotor. If you take it to a shop to do the work, ask for NGK or Denso parts though.

Xhadow

I know my answer is going to be different from what everone else has said but this may save you a lot of time and money.

I was having almost the exact same problem as you were. I thought my transmission was slipping so I changed the Transmission Filter. Well there were no metal shavings in the pan. Then I changed the sparkplugs which gave me slightly better mileage but my car was still hesitating.

So I purchased a new fuel filter and as I was replacing the old one I noticed that it was an original Toyota filter. which to me meant that it hadn't been changed since the car was new. After taking it off I blew threw it and it was very hard to do so but this muddy brown liquid came flowing out of the other end.

Needless to say I changed the fuel filter and I haven't hesitated or slipped a gear since. However I have ran a few fuel injection cleaners thru the system just to be on the safe side. I hope this helps because I was at a loss for a while.

Also for anyone wondering how I figured that if it was a Toyota filter it was the original one. In the owners manual the original owner (who had it for 10 years) had every service stapled to the back... no fuel filter I don't think the last owners took great care of it because my seats are ripped to shreds and the interior looks like it hasn't been detailed in YEARS. But I am about to fix all of that!!!

92ES5sp

The front bumper looks monotone green And your wipers are in winter mode