I have a 97 Ls motor in my 99 hatchback.When the engine is cold the idle is rough for a couple seconds then it starts idling at normal rpm this has been going on for a few weeks.Car still runs great it idles normal when engine is warm.I cleaned the IACV,TPS and changed fuel filter and the problem is still ongoing.Any suggestion would be great.

 

CEL codes?

Does the engine have an FITV?

 

No CEL.Whats FITV?

 

Click the link in my signature.

For engines that have one, the FITV maintains a high idle speed when the engine is cold.

 

No I don't have a FITV.

 

unless you have an aftermarket i/m, you have a fitv. check coolant level, your symptoms describe a problematic one perfectly

 

I have a stock intake manifold. FITV is for 96 and below motors. Mine is a 97

 

Does the CEL work?

Have you tried bleeding the cooling system?

 

Yes CEL does work. Cooling system been bleed correctly. Immature try and clean IACV again.