I step on the brake pedal and feels hard and sometimes the car drags

I did not explain myself more clearly and I am sorry for this. But it doesn’t feel like a brake booster issue because if it was an issue with the brake booster I don’t think the engine would feel like it has no power and it wouldn’t be doing it constantly even with the A/C off? It’s doing this mostly on hot days but only when the A/C is running.

As soon as the I start the engine and it’s hot with the A/C on, the rpm needle jumps up and down to 1,000 RPMs for about a second or two with the engine feeling like it’s surging. The needle then quiets down and stops moving and everything fine.

Then when I am driving the vehicle, I slow down, when I come to a gradual stop, at idle the RPMs jump to 1,000 RPMs and the needle is doing the same thing. For a split second, the car feels like it’s moving itself forward and the engine starts to surge. It’s scary because sometimes I can’t seem to stop the vehicle for about a second. Than it’s all fine and everything is smooth when I stop again. It just feels like the engine doesn’t have much power when I am driving with the A/C on when it’s hot.

With the A/C off everything is fine and smooth traveling. Braking is fine, RPMs do not jump and stays steady, I am able to slow down fine without having the car still move forward.

One other guy said, it could be the idle air control valve is not functioning properly. The A/C compressor turns off and on do to the drag on the engine. But with this car because it’s newer, I don’t know if the computer needs to be reprogramed or if it’s something simple and I could just clean the idle control valve.

I just checked the dealer with my vin number and they told me I don’t have a idle air control valve. I have a MAP sensor. If I disconnect the MAP sensor and idle smooths out could it be the MAP sensor that’s bad?

As for the brake booster, what do you mean by “You won't have brake assist but if this doesn't happen and smooths out then the booster is the issue”

Thanks for the explanation, it helps a lot because I am a beginner mechanic and try to fix a lot of stuff without any supervision so bare with me with all these questions.

As of today, here’s the news. I checked the brake booster and that seemed to be ok. Keep in mind, it’s almost close to 100 out today, so at idle I had my A/C running along time. Needle wouldn’t stop revving the engine at RPM, you can actually stand outside near the engine and hear it rev. When I went out of the parking lot to accelerate I can barely step on the pedal at first. I did notice when I apply the brakes, the car wasn’t dragging me this time and I was able to stop easy with applying the pedal.

I did some research and like I said above I don’t have a idle air control valve and that indicates it needs to be replaced when idle air control cannot compensate to smooth out idle with the computer. Therefore, I only have a mass air flow sensor and map sensor. Many other technicians recommended cleaning the mass air flow sensor or replacing it and that usually helped. So I bought a cheap aftermarket $25 MAF, that did not fix it and made it worse. Sent the part back, put the OEM one back in and what do you know... I cleaned it and was fine for a couple of days. But I still think it’s bad... So before I replace the mass air flow sensor for $60.00, any other things I should check? Isn’t it very rare a MAP sensor goes bad if you have a MAF sensor? And for the throttle position sensor, couldn’t that make idle unstable? Should I check operation of these sensors before replacing the MAF sensor just to be sure?

Thanks will let you know. I really appreciate this information.

Okay, I am across something else. I didn't bother to check the mass flow sensor yet because I don't think that's the problem because acceleration is smooth and idle is fine. I was doing more research and saw somewhere a worn-out timing belt could make RPMs act crazy at idle? This vehicle just went to 76,000 today. Could that be wearing out? I have only replaced one so far but that was on a vehicle with over 100,000. Not sure how to adjust the timing or pulleys because someone helped me with that. Do you recommend replacing it? If so, is there an easy process for adjusting the timing?

Kenny, if you are reading this thread, I want to check back with you. I was able to finally get around checking the mass air flow sensor, although it hasn’t given me problems. But I was curious to see if it was working so I looked over the specs you sent me. I did not get 5 volts between pin 4 and 5, it was more around 7.1. But I did get around 0 to 1 volts between pin 3 and 5 while revving rpms at idle and it was where it should be. The connection is clean and not damaged. I found a very slight splice at the connectors wire for pin 5. But the connector overall seems tight.