T-beast

I have a 92 SVX which refuses to IDLE. Starts fine and idle climbs to 1000-1500 rpm, for a few min, then drops rapidly to 500 rpm and idles very rough, or stalls. It seems to run OK at higher RPM. As the engine warms it won't idle at all. I don't get any trouble codes in the read memory mode. Does the 3.3 L have an Idle control valve, can't find any reference to it? Can't find any vacum leaks but it's possible.