my car won't go over 30mph.

Since the coil pack actually helped, problem is obviously ignition related .. It's possible the spark plug wires are breaking down upon acceleration .... Also > IF oil is ponding up in spark plug tubes (oil on spark plug wire boot when removed) valve cover *gasket set* replacement needed! .. Oil on spark plug wire boot and down inside the spark plug tube can cause misfire... [[Engine 'size' is always helpful.]]

Take a look at the fuel filter and pressure. Could also be a transmission problem.