I have a 1993 F250 four-wheel drive with a 351 Windsor and a 5 speed manual. Lately I have been having problems with it running. It will start but it will rev high and then sound like it's gonna die and will either die or rev high again and continue doing that till it dies. Sometimes when I start it, it will start up fine and run fine for a little bit but then when eventually start reving really high and then die. And then sometimes I'll be driving it and it will randomly just die. I have no idea what's going on with it. If somebody could help that I would greatly appreciate it.

 

I would check the vacuum lines. Mine did the same thing then would idle low and stall when I wasn't even in gear. The vacuum line going to the idle air controller was creased and eventually split. Changed it and I was good to go

 

The IAC on this vintage truck is electronic controlled by the computer, there is no vacuum connection to it.