1992 F150 W/5.0L engine, 165,000 miles. Upon starting the truck there is no high idle. When left to idle it surges and sometimes dies. Sometimes have to hold accelerator to the floor to get it to restart. I drove it five miles and it died when I pulled into parking lot, but it starts right back up. Scanned it, but no codes. Changed fuel filter and I added Lucas fuel additive, heat and filled both tanks. I've only driven 10 miles since adding, so it probably hasn't had a chance to take affect yet. I sprayed for vacuum leaks, but may try that again. Any help would be greatly appreciated. Thanks guys!
I would check the EGR valve. It can cause some of the problems that you are experiencing. You need to ensure that the valve opens and closes and is not stuck. This rascal should be located on the intake manifold.