2000 Mitsubishi Mirage engine

The check engine light was on and the code said egr valve. So I replaced the egr valve and egr valve silonoid and the car ran fine for a few days then the car began to run rough and the check engine light came back on. Well this time the code indicated the car needed a camshaft position sensor. FWell I replaced the camshaft position sensor and now the car wont even start!