if the oil or air temp sensor thinks it's really cold wouldn't the computer spray more fuel into the mix? and that would stall it out when ya turn the throttle open? could explain why it idles nice w/a tps reading of 270?
OR, after setting the idle stop screws, did you just stick the link rod back on or did you "set" that too. if you just hooked it up maybe it opened one of the butterflies slightly?