I have a1993 F150 XLT Extended cab full size bed that had the 302 in it. The person who had it before I got it cut the catalytic converter or of it and the idiots cut the y above the y making 3 cuts to have welded instead of just 2,, but anyways. I am having an issue I start it up completely fine if runs, idles down ok. I put it in to gear fine. I let off of the brake to go just as normal as it should be, but when I go and push the brake to stop, it dies, every time. I was told by somebody, that I should try to change the Air Idle Control Valve, I did, and it still does the same thing. My uncle told me to check the vacuum lines, and that is the next thing that I am going to attempt. I just thought I would create this account here and ask the world of Ford lovers if any of y'all have had an issue like this and maybe have had a solution to what it sounds like I'm facing.. Any advice will be greatly appreciated, Thanks for the time and the opportunity..
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When you step on the brake pedal, you allow the vacuum brake booster to operate. Vacuum from the engine is supposed to assist with brake application, but in this case there is a giant vacuum leak within the booster causing the engine to die.
To prove this, just unplug the hose from the booster and plug it so air can not get in and then with engine running, apply the brake . Brake pedal will be hard, but engine should not die.. If all this is so, booster will need to be replaced.

 

I thank you for your response and as soon as I get an extra minute, I'm going to put your advice to use and see what I come up with, thanks again. I've been flabbergasted on what to do.