Let $K$ be a field an $K<x,y,z>$ the non-commutative polynomial ring in 3 variables.

Question 1: Are there two polynomials $f,g \in K<x,y,z>$, which are sums of monomials of degree at least two such that the algebra $K<x,y,z>/(f,g)$ is finite dimensional?

For two variables we can take for example $f=xy+yx$ and $g=x^3+y^3$, but I do not know (or forgot) such examples for more than 2 variables.

(If possible we should also have (this is equivalent to $(f,g)$ being an admissible ideal) that there exists an $n \geq 2$ such that $J^n \subseteq (f,g)$ where $J=<x,y,z>$ is the ideal generated by x,y,z.)

Question 2: Let $f_i$ for $i=1,...,n-1$ be polynomials spanning an admissible ideal in the non-commutative polynomial ring in $n-1$ variables $x_i$. Can we find $g$ such that $<f_i,g>$ is an admissible ideal in $K<x_i,y>$?