Just picked up a 97 1500 5.2 automatic 4x4 for farm use with 120,000 miles. It starts hard and idles rough when cold or warm. No loss of power and as soon as I give it gas it runs and drives perfect. It does seem a little rich in idle and misses. It has newer plugs wires. It runs even worse when I first put in in gear or stop. When I’m driving at low rms and just a little gas it kinda shakes but when I give more gas it runs just fine? Doesn’t stall

 

Throttle positioning sensor may be going out or you need to clean the throttle body

 

Do this with the battery and throttle body disconnected.Then allow it to run with all electronics turned off radio, A/C, etc. This should allow it to learn the idle position. Let it run to operating temperature, meaning the coolant has reached its normal temperature as when driving.