Possible bad O2 sensor?

[Guitarlp]

There was another thread on here about the car surging in low gears. I wanted to get your input on if you think it could be the O2 sensor.

My car surges in all gears but is most noticeable in 1st, less in 2nd, less in third... and so on. When I say surge, I mean I can be driving 10mph with my foot steady on the throttle and the car will lurch forward and then slow down... almost like I'm taping my foot on the gas pedal to the beat of a song.

I just bought the car and it's at my friends shop while he's taking a look at it (1992 ST). He said the surging is normal on this type of car but it doesn't feel that normal. I'm sure it may surge a little... but not as much as it is.

Anyways, I did some research and found a few people had this surging problem from running rich. They claimed their car was surging and had terrible fuel economy. My car is so new I don't know about the fuel economy but it's almost on Empty and the trip meter is on 178 (I'm assuming it was re-set at the last fill up but I don't really know). If that's the case then my car may be running rich as well which could cause the terrible fuel economy and the surging.

Anyways, he asked if I passed smog and I said yes. He then said if it passed smog it's probably not the O2 sensor. But when I check my smog record my reading HC (PPM) is at 124 and the max possible for passing is 124 (meaning I just passed). I checked and this reading measures the amount of unburnt fuel leaving the exhaust. Knowing this, wouldn't it make sense that my car is running rich?

So what would you guys do? Would you try replacing the O2 sensor. I found one from RockAuto for about $50:
http://www.rockauto.com/ref/SMP/SMPD...html?SG360.jpg
Looks like a direct connection to the stock connectors. My friend (the mechanic) said using an aftermarket O2 sensor was a bad idea and would cause problems. He said I should go with OEM but that would cost somewhere around $200. Knowing this may not fix the problem, I am wondering what you guys would do?

[shortlid]

My brother just called me his '91 GT with the 2.2 and 5-speed is doing the same thing? Surging under load and at idle. Can't get it above 4,000 rpm. He was never able to replace the fuel filter in it and it has over 100k. It has the issue ALL my Toyota cars have. RUSTED SOILD FUEL FILTERS!!!

Any way to fix it?

[ShawnM]

Ive never seen a bad o2 sensor cause a surging problem. It could cause it to run a little rich or a little lean tho. I would look elseware for the problem. A plugged up fuel filter would be most obvious at higher speeds or acceleration, basically when the engine needs the most fuel.