i will never change plugs again.. stumped..

[two40guy]

alright.. so i had a problem a while ago where i would WOT and my car would rip through boost but then start to backfire and power would drop off.. i boost leak tested it and it went away and ripped would still hiccup at very high rpm near redline but thats it, and every so often very randomly at idle it would spit once or twice and that would be it, well tomorrow is my first track day so i figured what the hell ill change plugs it might fix the spitting problem and theyve gone through a ton of crazy boost leaks so it was probably just time to change them, i changed them and thats when my car started running terrible, i changed them and it idled smooth so i was pumped but then revved it and instantly when you rev it it drops to 5 cylinders goes back to idle and idles on 5.. here's what ive done/found out thus far,

coils and plugs all spark

spark plugs are black around the the bottom of the threads
but are white and dusty on the tips. all 6. (indicating lean?)

Tested TPS and at closed throttle had a reading of .59v and open
.79v. way wrong.. tried adjusting it but it wouldnt really change
and when ever the key is on its at a constant 9.5

i checked for boost leaks - None

all coil harness grounds and stuff are connected..

Im confused litterally all i did was change plugs.. i got the same exact plugs and everything.. gapped the same. im getting frustrated and not thinking of things, any suggestions would be greatly appreciated. TPS is making me very iffy though.. putting my money on that.. sorry for the rant.