  Let $M$ be a smooth, orientable, closed, connected $4$-manifold and suppose
that $H_1(M;\mathbb{Z})$ is finitely generated and has no $2$-torsion. We give
a homotopy decomposition of the suspension of $M$ in terms of spheres, Moore
spaces and $\Sigma\mathbb{C}P^{2}$. This is used to calculate any reduced
generalized cohomology theory of $M$ as a group and to determine the homotopy
types of certain current groups and gauge groups.
