Poor acceleration while in open loop

[LB2387]

I have a 1987 chevy r10 with a 350. When the engine is cold it will stumble when trying to accelerate. It idles smooth and its not missing. Only stumbles when trying to accelerate. feels like an ignition issue. Once the truck gets up to operating temperature, it runs perfectly. Just replaced pickup coil and ignition module trying to fix it, but the issue is still the same. Other things that have been recently replaced are coolant temp switch, fuel filter, fuel pump.

 

[mrnapolean1]

I have a 1987 chevy r10 with a 350. When the engine is cold it will stumble when trying to accelerate. It idles smooth and its not missing. Only stumbles when trying to accelerate. feels like an ignition issue. Once the truck gets up to operating temperature, it runs perfectly. Just replaced pickup coil and ignition module trying to fix it, but the issue is still the same. Other things that have been recently replaced are coolant temp switch, fuel filter, fuel pump.

Mine is doing the same exact thing. Expect mine has the 262 CID 4.3 V6.
It trips over itself until it gets to operating temperature.

 

[89Suburban]

What have you done for diagnosis so far? EGR valve issue possibly?

 

[mrnapolean1]

What have you done for diagnosis so far? EGR valve issue possibly?

I haven't done anything other then I ran some Seafoam thru it to see if it would clear it up.

 

[LB2387]

I had almost the exact same problem almost two years ago. It turned out to be an issue with the distributor. Replaced with a new one and it ran great up until a few weeks ago and I started having what seemed like the same issue. I tested the pickup coil and it was out of spec so i replaced it, but it made no difference. I also replaced the ignition control module but still not any better. EGR valve and EGR solenoid both checked out good.

 

[bucket]

Replaced the cap/rotor yet? Cheap ones don't last very long usually.

 

[89Suburban]

It's not throwing the engine light or a code on?

 

[mrnapolean1]

Replaced the cap/rotor yet? Cheap ones don't last very long usually.

I am due for a tuneup any day now that you mention that.
Ill have to round up the parts and do a tune up.

Plugs, Wires, Cap, Rotor, Fuel Filter, and air filter if it needs one.