First thing to do is check for any stored dtc's(codes)
The PCM grounds for being clean, tight, and in their proper location
The vacuum hoses for splits, kinks, and proper connections, as shown on the Vehicle Emission Control Information label. Check thoroughly for any type of leak or restriction
The Mass Air Flow (MAF) sensor installation. The arrows on the plastic portion of the sensor must point toward the engine.
The engine harness wiring and terminals for proper connections, pinches or cuts
The PNP(also called neutral safety) wiring is properly connected to switch at transmission.
Any dangling or disconnected portions of vehicle harness.