on a cold start my tachometer doesn't move at all

[boostedB]

I've been having some problems with my car even though it runs fine if it wasn't for the check engine light.

The first problem is on a cold start my tachometer doesn't move at all while I am driving to work. The check engine light comes on after 5 minutes of driving or so. I can also hear my engine idling higher then usual at a stop.

At around lunch time I start the car and my tach magically starts working again I see its idling high around 2500rpm and eventually goes to 850-1000 and the check engine light comes back after I drive off.

So what is causing this and how do I fix it?

I've also been searching for a OBD 1 scanner any recommendations?

Heres an un-photo chopped picture

 

[pooker]

Iac or an improperly hacked maf, a leak around the throttle body take your pic.

 

[boostedB]

Thanks pooker I was thinking the IAC too

 

[boostedB]

To add some information to this:

This only happens during a cold start. The engine will rapidly bounce back and forth between 2000 - 2500RPMs. This will go on for about 1 -3 minutes. After that, the car idles like normal. The CEL isn't my biggest concern. I want to see if I can find the root cause of this idle fluctuation.

Things that I've checked:
I read the resistance on the IAC and got 32ohms (good?)
All vacuum lines look fastened down securely (couldn't confirm if there is/isn't a leak)

I read somewhere on here that this might be the case of a bad temperature sensor. And there are multiple temperature sensors? Maybe the temp sensor is constantly giving a high temp signal so that the idle control thinks the engine is warm when it really isn't?

Any other guesses?