Shudder or hesitation

I posted this on another site and got no takers can anyone help?

Here is the story.
With the jeep in drive foot on brake and A/C on I feel a shudder almost like rpms drop, but I don't see it on the gauge. This is not like a full miss just a slight shudder for lack of a better word
Without A/C it almost never happens and in park or neutral I have not felt it.
Just started a few days ago.

Could it be the the csp starting to go bad? Or Iac

I would start with a thorough cleaning of the idle air control and the throttle body. They get carboned up over time and miles. The IAC may not be up to the job of holding you where you need to be with a load on the engine. No guarantee that it is going to resolve this, but it is good maintenance regardless. Here is a quick "how-to".
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The Idle Air Control (IAC) is mounted on the back of the throttle body. The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

“Gently” wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled

Reinstall IAC and check idle quality

Thanks I will give it a try.

That is the a/c clutch engaging and putting a load on the engine.

You will see the volt meter drop accordingly when a/c clutch is engaged as well.

Both normal actions IMO.

my2monkeys said:

That is the a/c clutch engaging and putting a load on the engine.

You will see the volt meter drop accordingly when a/c clutch is engaged as well.

Both normal actions IMO.

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Yeah, I had that same thing happen to me on a long road trip last week. I thought it was the fuel pump going, but when i turned the A/C off it stopped. In my opinion , your explanation makes sense.