suffered the same issue with my 17.5 car on a tight carpet track. this is what i changed
Shocks
45wt oil
#3 pistons
gold springs
fwrd arm mount 3b
Rr arm mount 1b
Yes, this is 8 deg of caster!!
i also removed the rear sway bar.
this improved my fast lap by .3 and top 20avg by .2 . Everyones driving style is different so....