90 s10 pickup problems...help!

[89ShelbyGuy]

Hey guys...i have a friend that has a 90 s10 pickup that has the 4.3 FI motor. His problem is when you first start it up with its cold..AND with it being cold outside, the car starts up normal but will idle like it has a cam...then once it warms up, its fine....now if its warm out side...like really hot, it wont even have bad idle....anyone have any ideas on what to check?

[black86glhs]

Look at the coolant temp sensor.

[turbovanman]

Any codes?

Check Coolant sensor as mentioned or the wiring, its by the thermostat housing. Check vacuum lines and check lines to the MAP.

[89ShelbyGuy]

No codes. I will have him check it.
Thanks!

[black86glhs]

I have also seen a bad injector cause issues. With it running, disconnect one of the injectors at a time and see if how it runs changes. It may get better or worse.