1988 Chevrolet Truck • 220,000 miles

I have an 88 chevy scottsdale 350 v8 4x4 that when sitting and switching through gears it will stall but start right back up. Can't not figure out what is wrong with it any info would really help. I have changed the distributor rotor and cap the air control valve. Ive checked the pcv and its still in working order. I don't know what to check next some told me it could be a vacuum leak but I can't find one.
July 18, 2013.

Yes, a vacuum leak will cause this problem. Also, please keep in mind 88 was a long time ago for me, but I believe it has an idle air control valve (IAC). The IAC is responsible for maintaining vehicle idle.

We've changed the iac that made it to were instead of the truck stalling when coming to a stop or slowing down to were it just now stalls when your switching gears.

Jul 18, 2013.
That's not good. Have you checked for vacuum leaks?