Your hard start may be due to a bad check valve in the fuel pump causing fuel pressure to leak off. The problem with the tach may be a bad PCM or a bad Cluster. Put a fuel pressure gauge at the test port, check your fuel pressure with the car running and check it with the car off, the pressure should not drop more than 2psi for ten minutes, if it does drop, you'll need a new fuel pump. Another thing it may be is that if you arent using the right gas, if it has too high an alchohol content it may be causing problems. Because your car has a supercharger, you should be running premium instead of regular.