Chilly Weather Trouble

[CharlesB]

Folks!

My mechanic is having a bit of a problem locating the source of a cold
weather (<40 Deg F) problem with my  '87 4kcsq with 100k+ miles. When
cold it starts ok, but shifting from 1st to 2nd then to 3rd it feels as
if its not getting gas (sputters). After its warmed all is fine. It's
like the fuel filter is clogging with some 'bad' gas. That of course has
been replaced.

Anyone have some ideas?

Chas Boehm '87 4kcsq