o2 sensor issues emergency please help lol

ok let me start off by saying if theres a thread for this already i apologize i havent been able to find any that relate to my issue.
so first let me start from the beginning. i had no downstream was missing wgen car was purchased so got a ebay special for like 30 bucks problem solved. actually it was just the beginning after running 87 octane for about 6 months i learned thr octane is compressioon related. so ive been running 93 for past 3 months give or take started a job at autozone ran obd2 scanner to see what my cel was on for. it was a plethora of thiing p1166 heater failure b1s1 and misfire codes for all four cylinders. recommended coil packs and o2s. i replaced coil packs with napol performance coil packs and a cheapo upstream. coil packs got rid of all the misfires but wheni inistalled upstream o2s i now got a p0134 high vboltage no activity code so after being told the k series are funny about having denso i bought a denso upstream o2s and replaced it with that one. now after disconnecting battery and installing denso sensor i now have all my misfires codes back and the p0134 for b1s1 i have aftermarket test pipes no cat no codes for downstream sensor no noticeable misfires that i can tell i havent the slightest idea as to what it could be going to be taking t to import specialist in a few days but figured id try the forum out. and see if anyone hgas had same issue and what their fix was. theres also possibility of flaahed ecu as my vtec seems to kick in aroun 4500 rpm and rev limiter hits around 8k and from what ive researched and been told vtec should be aroun 5300 and rev liimiter around 7300 aside from some shotty cai and the headers/test pipe theyre the only actual performance mods i know of. ive been told i need to do the defouler trick but im not getting any codes for the downstream and ive been told never put defouler on upstream. whats wierd is at first wheni put denso sensor in and reconnected battery and drove it seemed solid exhaust sound was different seemed more responsive and all around solid the after getting on it a bit i pull back up to driveway and lights back on car sounds different and runs different. now light isnt my issue its the gas mileage thats dribving me crazy cause it seems to get gas mileage like a v8 not a i4 lol and with 93 octane at almost 3 dollars a gallon by me really would like my mpg to be as good as they possibly can.

ps sorry for crappy punctuation and other repairs aside from suspension and clutch are the down stream o2s and iacv doesnt seem to be in limp mode but def feels like its restricted and not at optimal performance and would really love to have all my power and it properly adjusting a/f ratio so im not wasting gas and money thank you in advance and again sorry bout crappy punctuation and some spelling error in a rush gotta go to bed soon for work in am lmao

1) I wont get in to the gas ordeal.

2)P1166 - Code for Bank 1 O2 sensor 1. Which is the primary O2 sensor. - Did you have a code for the misfire in all cylinders? Mine had the same code but was just 1 coil pack was bad.

3)Vtec kicks in at 2800(i-Vtec engagement with 4700 Vtec timing shift) but it is a low vtec, not like the B series Vtec. If you have a flashed ECU, should have a Hondata marking on it.

4)Napol Coil packs? I know nothing about these.

With the V8, is it happening at Low rpm or high? Is it happening at a stop?

Let me know if you need any help. I am in the Tampa Bay area, and work for a local race shop on the side.