Question

I have a 1987 chevy suburban 1/2 ton 4wd with a 350 engine. I am currently experiencing a problem with the engine where the idle is very erratic (races up and down all on its own) and quite often stalls. When it stalls it is very hard to get started. When I finally get it start its appears as if it was flooded with fuel. I have sensor tester that I purchased locally. I have replaced the throttle position sensor because the tester showed it bad. The new checked good but problem still exists. I then tested the idle control motor and I could not get it to respond according to the tester so I assumed it to be bad. The new one did not respond any differently but I replaced anyway. Problem still exists and actually getting worse I believe. I had a spare ecm module so I replaced it just for trouble shooting but to no avail. I have shopped around trying to find the original factory service manuals for this vehicle but they seem to be out of print. Please help if you can.