I have a 95 chevy 1500 4x4 5.7L 145,000mils. It's been running good/bad for a few months. It will start right up and idle ok in park but as soon as I put it into drive it stalls out. If I put in drive and try to keep it running the rpms will just go up and down hard then stall out. I have put a new O2sensor, cap, ignition mod (under the cap), the last thing I just did was a new coil and still nothing??