2G 420a Can't Figure Out What's Wrong...Idle Drops Close To 0 When Coming To Stop...

[EagleTalon24]

It all started with exhaust popping on idle. In park the idle stays fine but once I start driving and come to a stop the idle will change up and down and will be on the verge of 0 but will resist stalling. When driving freeway speeds the idle does not surge or fluctuate only when coming to a stop.

I have cleaned my throttle body. I've checked and gapped spark plugs, wires, ignition coil. The car has a new fuel pump as well and am getting 45 psi fuel pressure. I also installed a new fuel filter.

I've checked my MAP sensor, and replaced my air intake temperature sensor because my check in engine light showed that, now it went away.

Engine Compression is 120-130 on each cylinder.

I am not sure what can be causing this sputtering? I can't seem to figure it out...

 

[spyderdrifter]

I would do a compression test and leak-down test to check for leaks or low compression too. Sounds like you got plenty of spark and fuel, all that's left is compression.

 

[EagleTalon24]

I would do a compression test and leak-down test to check for leaks or low compression too. Sounds like you got plenty of spark and fuel, all that's left is compression.

I forgot to mention in my original post, I checked compression a few days ago and compression ratings were 125-130 all the way around.

My car has 135k miles

 

[spyderdrifter]

Is that normal for a 420? My current 420 is the first one I've had since 2005, and I never got into much mechanically with that one, and so far only have transmission issues with the current one, although I have way more knowledge and tools than the last time, so I'm prepared now.