1990 Trooper Won't Idle Until Warm

Hello all,
I have a 1990 Isuzu Trooper with the 4cyl and the 5 speed manual. After it sits long enough to cool down some, when I go to start it again I have to give it some gas in order to keep it running. I won't hold an idle until it's warmed up some. Just wondering if anyone would know what to do to fix or help remedy this problem.

Thanks in advance.