Variant of 3-SAT is NP complete?
I have found a reduction from 3-SAT.

For every instance of variable $y$, I will put a new variable $y_i$ in its place. Suppose there were $K$ such instances then after replacing each instance of $y$, I will add clauses  $\bar y_1 \vee y_2, \bar y_2 \vee y_3, \ldots, \bar y_K \vee y_1$. This ensures that $y_1,\ldots,y_K$ will be assigned the same value.