Stumble when cold

[Stacy]

Hi all.

 

Lately I my 86 5kcsq has had a stumble when cold. It starts fine and idles
fine. But any application of power, and it will stumble for a few seconds
and then smooth out. This only happens when my engine is less the 75% warmed
up. 

 

Sometimes the stumble will be serious enough to cause a backfire. The
problem goes away once the engine is warmed up. Any suggestions would be
much appreciated, any extra information that would be helpful in diagnosing
this I would be more then happy to provide.

 

Thanks in advance!

 

Stacy