1989 Dodge Dakota - Runs Bad When Cold

when engine is cool below 70 deg it runs real bad like two cyl, and when it warms up it run’s real good?

A statement with a question mark is not a question.

Tells us way more about your truck and your problem and maybe we can help.

Is the check engine light on?

I always run better when warm rather than cold. Warm good, cold bad.

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My top of the head guess would be a fuel injection issue. The fuel mixture might be off slightly when the engine is cold. Older vehicles had chokes for that purpose but newer ones rely on computers.

I’m the opposite. I overheat!

Intake air sensors can fail and cause similar problems on Fords of that time. Possibly Mopars also. Total failure of the Ford IAT sensor results in a 210* signal to the ECM causing engines to idle rough and stall idling at a light until fully warmed up on a warm day and never running well on a cool day.

Does your truck have the ECM under the hood near the battery?

If you had unmetered air getting into the engine (like a vacuum leak) that might be the symptom. A too-lean problem will show up when the engine is cold like gangbusters. First the O2 sensors probably aren’t working yet (they need to be warm to produce accurate signals) so it is running open loop (sort of like it is blind), and the cold engine is more sensitive to a lean mixture than a warm engine anyway. So that’s where I’d start, look for a vacuum leak of some sort into the intake manifold. You could try spraying starter spray to located where the leak is occurring. If the engine speeds up, that’s where.

Maybe a vacuum leak.