Stumble and stall at slow speeds

[dheavychevy38]

The problem started end of last summer when I parked the truck for the winter. It's a 1987 k5 with tbi 350. The motor is bone stock and I have installed new plugs and wires. The truck runs great in park while idleing but if you put it in gear it starts to lope. The biggest problem is when you drive down a road at like 25 mph for a mile or more and then come to a stop it usually stalls 50% of the time. I have noticed a knock from the inspection cover area on the trans on start up. Any ideas ?

 

[xenomarine]

I have something similar. Mine stalls when it's cold, and when it's warmed up it sometimes idles really really low, low enough that it almost stalls when I turn the wheel. I've attributed it to my trends and torque converter slowly dying.

 

[76zimmer]

stalling and rough idle may be caused by a vaccum leak....start with the simple stuff first...take a can or brake cleaner and spray it around fittings, hoses, etc...anywhere a vaccum leak has potential. Don't rule out a cracked intake manifold from the bottom side...I've seen it happen...the engine wants to stall when cold and mileage goes down somewhat, and maybe an increase in oil consumption.

 

[smier]

First off, check the free stuff first! Vacuum leaks, double check your plug wires, and most importantly scan for codes! Your truck may be trying to tell you something. There are several possibilities that can cause issues like you're describing, it's a process of elimination, and may be a combination of several problems...

Don't forget to check the EGR Valve and EGR solenoid, if they fail or are sticking they will act like a giant vacuum leak. I didn't realize my EGR valve was sticking slightly, I checked and it seemed to work, but it would act up and stall exactly like your describing... Check them first, they aren't cheap. In my experience with these TBI setups, a vacuum issue will also cause your idle to be too high, hard to tell without a tach, but it will usually slam into gear when you take it out of park.

Check the stuff first, don't just throw parts at it, it gets too expensive and often times doesn't solve the problem, it just leaves you broke and frustrated.

 

[azblazer]

Sounds like a egr valve taking a crap to me....