Bad IAC?

[35Remmy]

So my 99 4.0 OHV is starting rough in the morning or whenever I let her sit a while, like leaving for work.

The motor is "chugging"...especially when you put it into gear for about 10 seconds, then all is fine.

My IAC started to mooooooo again and I was wondering if there could be a connection. Last time it started mooing I cleaned it and the noise went away, but the motor ran fine even while it was dirty.

No CEL...I ran codes just in case and nothing is stored.

My upper intake manifold gaskets are new, too.

 

[BrooklynBay]

Did you clean the MAF sensor?

 

[35Remmy]

Brooklyn...I cleaned it about 3 months ago when my truck was pinging...it still is pinging, can't figure it out.

 

[BrooklynBay]

What kind of gas do you use? Some engines are equipped with a knock sensor, like the 3.0L on the 89 Mercury Sable.

 

[35Remmy]

I run regular at whatever gas station I pull into. I've tried no-name gas, sunoco, exxon, etc...different octanes, etc.

My #4 and #5 cylinders are running lean...spark plugs at those cylinders repeatedly cover themselves with white deposits.

Changed my upper/lower intake manifold gaskets.

Compression #'s are perfect.

Cleaned MAF. New plugs/wires

I'm wondering if I have a sensor (like my MAF) that is running just below what it is supposed to, just enough to NOT turn the CEL on.

Although, if that were the case, why would ONLY the #4 and 5 cylinders be leaning out? I keep thinking I screwed up the intake gaskets.

 

[35Remmy]

Oh, I've seafoamed numerous times through the hose on the bottom of the throttle body as well as the brake booster line...with LOTS 'o smoke.

Problem is, this 4.0 runs GREAT. It's weird. Pinging stinks, though.