We just bought a 04 grand prix 3.8 3 series. The day after we bought it, it died. It had a random idle issue, would cut out when cruising down the highway. Then it just died while driving. Now it won't start. Did some research, we replaced the MAP sensor and put in 3 new coil packs and wires. We have a MAF sensor coming tomorrow. No codes are showing! This is our only mode of transportation. Help!