I just had a crate 5.0 put in my 1988 f150 2wd. Idles fine with a few stumbles. My problem is when I turn my blower fan on or lights or wipers basically all the things electronic it stalls the engine. With none of that on it runs like a top. The battery and alternator test was good. Ive added ground cables to every possible place I know of. I've checked the AC compressor and it's free spinning. Can't find any vacuum leak's. I'm at a loss as to what the problem could be. Any suggestions would be great. Thanks.

 

If you use a multimeter set to volts dc across the 2 battery posts you should see about 14.5 when it's running. That'll be your alternator output.
Have someone turn all those things on - or one at a time - while you watch your alternator output.
Could be a bad alternator or possibly a misconnected wire.
That'll be where to start, anyway.

 

It's 14.5v. With everything on it drops to 13.2 or 13.5v. Its the worst when it's cold. Takes it a while to stop idling up and down. I can't even press the gas to far without it stuttering in the morning. Once it is hot the with everything on it runs fine until I take my foot of the gas or come to a stop and it stalls.