I've only had my 93 for about 6mths or so, but occasionally during the summer it would have erratic idle and would stall on me if I tried to take off before it would even out. But now, in the cold weather, it is doing the same but even after the idle levels out it will run rough and stall while driving until the engine reaches normal temp. I have to two-foot it at stops to keep it from stalling, but even two-footing doesn't work sometimes.

If it stalls from the erratic idle, it will start right back up again. However, if it stalls while driving (after the RPMs evens out) it will take about 10-15min before it will start again. And as luck would have it, the last time it did that I was in the turning lane at a stoplight. Oh the fun...

I replaced the plugs with Motorcraft Iridium, wires with MSD and changed the fuel pump during the summer, it was doing it before and after I replaced them.

 

My first thought would be check for codes. I would be inclined to think it's either the Throttle body or a vacuum. But I haven't had this issue so I would check for leaking vacuum lines and clean the throttle body since it would be about free. I'm sure someone else will chime in.

 

Being a '93 it is OBDI and it isn't showing a check engine light.

Once the RPMs level out I will try squirting the hoses with either carb cleaner or WD-40 and listen for the change in RPM.

 

There is a Sticky at the top of 1987-1996 F150 section that shows you how to pull codes on OBDI. You could have some stored codes without tripping the light. Most auto parts stores sell throttle body cleaner. Read the can carefully, you don't want to get it on the sensor or it could mess things up.

 

It was the throttle body. More gunk in there than I could imagine.