hesitation/mis at 3,500 rpm

[04V8Mustang]

Trying to diagnose a vibration with my '96 and have the car on jackstands. Running the engine up slowly from idle to about 4K rpm, I noticed that around 3,500 rpm the engine sort of stops increasing in rpm. I have to then give it more gas than I was when climbing to 3,500 rpm. It then works past 3,500 and seems like it takes similar throttle input to climb as it did before 3,500. Is this the IMRC plates causing an issue? Coils?

 

[2DXTRM]

Check and a clean the IMRCs first if they already havent been done so.

 

[04V8Mustang]

Thanks. Can you actually replace the vacuum actuators?

 

[1996slowbra]

+1 on IMRC's i had the exact same problem on mine before i cleaned them. And im not sure if you can replace the actuators, i have actually never heard of them going bad, they are mounted on the bottom of the intake manifold so you can check them out when you get it off.

 

[04V8Mustang]

Thanks.

 

[ksigatmsu7f02]

The IMRC controller isn't a vacuum actuator. It is an electronic controller that does at times fail, although I'm not saying that is your problem. The people on here will go back and forth on deletes, especially with stock gears. I have them and stock gears and it is working great for me. Slight loss lower than 3000 but a tune will make it much less noticable.

I would suggest if you're going to pull them off just delete them, especially if you plan to add some gears in teh future.