I have an 05 Pacifica, just cleaned out the throttle, using 91 octane gas, installed a cold air intake, and used the Lucas deep clean injector cleaner. When I accelerate it feels like I'm towing a boat, but when it gets to about 4-5k RPM's the car pickups and gets moving like I just pulled the pin on the hitch and dropped the boat so to speak. Any thoughts? No check engine light either. I only have 59000 miles, and I was thinking it could be spark plugs? Fuel Filter, but since its inside the take could it be clogged? Injectors dirty? Help!!!

Thank you.

 

Did it do this before all the cleaning?

 

Yes. It was actually worse then it is now. Its gotten better, but in the morning, it feels like it "hick-ups" when accelerating before it warms up. Not even giving it a lot of gas either. The "hick-ups" go away once its warm, but then I get the burst of acceleration at high RPM's. I want to say fuel filter, but since its in the tank, it shouldn't be a regular item to replace.

 

Maybe throttle position sensor?

 

I think you may have two things going on. The cold engine stumble is probably nothing do worry about. Mine is the same, but other cars do it too. If you have been driving for a while, you probably remember it being worse back in the day when engines had carburetors. I think there is just a little too much fuel, causing the stumble. Letting it warm up a bit would likely cure it.

As for the higher RPM issue, I think you are feeling a feature built into these engines. They have a variable intake tract. The theory is complex too much to describe here, but the short story is that you want to have short intake runners for good throttle response at low RPMs (Throttle plate close to intake valves). For higher torque, these motors have a valve that automatically opens at a specific RPM level, which opens up a longer intake tract, which will provid more torque. You can feel it when accelerating on a freeway on ramp, especially if it's up hill, and you are getting into the throttle. Feels almost like a downshift. Again, it is nothing to be concerned about, supposed to work that way. (I think).