96 chevy 1500 not running well when first started.

This is an odd issue. My 96 chevy 1500 recently had the
anti freeze flushed and changed. Has been running great
since. About a week. Then Saturday morning I had to
drive in the snow storm. got where I was headed and
turned the car off. 3 hours later the problem started when
I turned me car on. It started fine but the engine was
stuttering for lack of better term and wouldn't get passed
30-40 mph. After letting it run and driving around the
parking lot it started running fine. Now the passed 4 times
I've started it it's done the same thing. 5 minutes or so of
troubled stuttering and then it works fine. Tried warming
the car up first and it makes no difference.