New member/new truck, some questions

Hi All,
Recently picked up a '98 Tacoma SR5, 2WD, 2.4liter V4 with 132,000 on her.
I am in the Northeast but truck came from Florida and is ridiculously clean.



A few days after buying it, the CEL came on, with the 420 code "catalytic system below threshold bank 1" or something like this.
Have done a bit of reading and seems most likely either the cat or the upper 02 sensor. Going to try to run high-test gas in the next tank and see if it helps.
What else should I do? No way can I spring for an OEM cat.


I changed the manual trans fluid yesterday (PITA). Calls for 2.7 quarts.
Is it true that fluid should be filled until it starts to overflow out the fill hole?
I put almost all 3 quarts in (spilled a bit and couldn't get 100% out of each bottle given the angle) and didn't get any overflow. Am I OK with what I've put in?

Thanks guys.

 

Welcome to TW ! I'm not ignoring your question,I just dunno n'ought to give you the answer...