02' Dblcab 4x4 taco 3.4 only 34K miles, K&N cold air & Gibson Cat back - Due to crappy gas mileage and sluggish acceleration I recently cleaned the MAF & Throttlebody, changed the fuelfilter, used 1/3rd can of seafoam on the top end and the rest in the gas tank. It's better but not back to what it should be. I'm thinking O2 sensors would help. Had a check engine for about 3 days 10K miles ago and about 5K after the filter & cat back install but never read the code. I've priced O2 sensors from $365(Bosch at Advance Auto) to $26(Denso on ebay, would need to solder the plug on). My question is whats the most affordable O3 that comes with the plug already attached?