1990 Silverado Ruff Idle

[bigchevyman]

hi i have a 1990 silverado i have replaced tps spark plug wires all my distrubuter and i o2 sensor and i fixed my vaccum leaks i dont know what the problem is when it is cold it has a ruff idle but after it starts to warm up it doenst do it any more but is still hesitates at the bottom and has a loss of power but some times like for a few minutes it will run really good i have no idea what to do and i have changed the chip and map sensor i have no clew what else to do i havnt replaced the iac or the the sprark plugs thats about all i can think of