Bensher

i have a 1999 Jeep Grand Cherokee Limited 4x4 4.7 V8 it has ran GREAT for years but recently it has been less dependable... last week it started shutting down randomly for no apparent reason, but when it shut off i wouldnt even know because all the gauges, the radio, and A/C would all stay on...sometimes would start right back up others i would have to wait 20-30 min, once it started again i could drive it for 500ft to 20+ miles and it would do it again....so far i have replaced the Crankshaft position sensor, Cam Sensor, New battery and did an oils change, and thermostat.... i dont know much about cars so i replaced all that from online discussions and forums i dont now whatelse it could be???? one guy said it could be the PCM but 6 others said no way so i dont know what to do next... any thoughts???? Thanks