Check Engine Light/O2 sensor??

Hi, i'm new here... but i'm having a problem with my 1995.5 Toyota Tacoma 4x4.3.4 V6 3" Body lift with 33/12.50/15s and 267,000 miles on her! She gets me where i need to go. But lately ive noticed that when i start her up and wait a few minutes for it to slightly warm up, I leave my driveway and turn on my side road that leads to the main road and go to pick up some speed and it bogs down a little bit. So i let off the gas and hit it again and its fine.

Its been like this for about a month or so... Then today my check engine light came on. So i took it to Advance Auto and they said it was both Oxygen Sensors. And ive been noticing poor MPGs.

One problem is... I only see one RIGHT in front of the CAT, I dont see anything behind it, all the way back to the muffler. The guy told me there should be one on the exhaust manifold. Well i dont see it... I see a place for it. Theres a flat plate there but no sensor hooked to it ( I can post a pic if needed). But then that would technically make it 2 in FRONT of the CAT. so im confused.... But i didn't lay on the ground yet and look under, it might be on the far side of the exhaust, but i was thinking it would be on top like the other one is.

I dont have a lot of money, so it would take me a while to save up to buy anything. I think i can get the $60 it would cost for me to get 1 sensor. But is there anything else i should do?

THANKS FOR ALL HELP IN ADVANCE!!