2G 420a Very Bad Engine Sputtering Between 2000-3000 RPM

[EagleTalon24]

The sputtering is very noticeable when you are at a stop and start to accelerate.

When at idle, the idle will stumble down rpm and then come back up. I have taken it to a shop and they still were not able to diagnose what was wrong.

Here is what I have checked and a few things I have replaced.

plugs/wires
ignition coil
New MAP sensor
Cleaned Throttle Body
New PCV Valve
New TPS Sensor
New IAT Sensor
New Crankshaft Sensor
New CamShaft Sensor

pressure is around 40 psi

I am all but lost at this point.. The only thing I can think of is bad fuel injectors. Any advice would be apreciated.

 

[EagleTalon24]

any advice? the shop I took it too couldn't figure it out. I hate going to different shops and spending my money and them coming up with nothing

 

[EagleTalon24]

I hear a knock under the car, not by where the engine is. Checking the catalytic converter

 

[Doomchild]

while not entirely similar problems, I recognise the rpm issue as mine had it as well when trying to fix the stalling problem.
thanks to the info from a member on here, it's now idling at stable rpm.

http://www.dsmtuners.com/threads/summer-plans-need-some-advice.512336/#post-153651282

checking the IAC/ISC with the multimeter showed it was faulty, luckily i had a replacement ready.

couldn't hurt checking

 

[EagleTalon24]

while not entirely similar problems, I recognise the rpm issue as mine had it as well when trying to fix the stalling problem.
thanks to the info from a member on here, it's now idling at stable rpm.

http://www.dsmtuners.com/threads/summer-plans-need-some-advice.512336/#post-153651282

checking the IAC/ISC with the multimeter showed it was faulty, luckily i had a replacement ready.

couldn't hurt checking

there is a loud clunk under the car by the catalytic converter/muffler. Very SLOW acceleration especially when going uphill.