Just bought a -99 Trans Am and I am having som trouble starting it up.

When I turn the key it fires up right away but immidiately dies again. I have to give it some gas to keep it alive and after about 5-10 seconds I can take my foot of the gas without i dying. The idle swings up and down around 1000 rpm for another 10 seconds and then it stabilizes at about 1000. Driveability is not affected and it behaves completely normal in every other aspect after these first 20-30 seconds.

Doesn´t matter if it´s warm or cold, same story if I turn it off and then starting it again.

No SES-light comes on either.

Any ideas what might be wrong?

 

I'd take a look at the iac valve (idle air control). It may be shot or drifted out of spec, dirty possibly.

 

Yup I'd do the same....get a can of MAF cleaner and soak the iac valve down and clean it, also clean the MAF while your there.

To reset the iac, unplug it and turn your key on, wait 10-15 seconds, then turn key off.
Plug sensor back in and turn key back on for 10-15 seconds again, turn key off and now your iac is reset.

 

Removed IAC, cleaned and reset it, no difference.

However, took the car to work today and the temperature has dropped to about 1 degree Celcuis (about 34 Farenheit) here in Sweden. Now the engine starts like a charm, idling at about 1200 at first and then slowly dropping til 1000.

I suspect some kind of temperaturesensor might be faulty. Any tips on which one and where it´s located?