The catalytic converter went on my sons 2007 HCH. The RPMs would rev high but car wouldn’t get past 40 MPh. He waited to mention this until he couldn’t get it above 15mph. We took it in had it replaced along with the O2 sensor.

The car is now back to not getting above 40mph.
When driving it one thing I noticed is it would be driving normal for the first few minutes and then that’s when it’s like something kicks in and the car fails to accelerate properly.

Spark plugs, coils, cvt fluid and oil has all been changed within past 30 days.

What would be the next thing to look at

 

You 100% certain your oil level is between the marks?

You use the expensive iridium spark plugs and change ALL EIGHT?

You use the Honda or Hitachi coils (all 8), or junkers off amazon/ebay?

 

Oil between two dots and used 3.5 quarts 0W-20
Changed all 8 replacing with NGK’s
Hitachi’s and did compression test on each, all read 180

OBD reader is not showing any error codes either

 

Excellent.

Do all warning lights illuminate at power-on prior to start (IMA, CEL in particular) and turn of after the car starts?

I checked the symptoms in the service manual for low power. If CEL is working (as above), but is off with no DTC set:

Check fuel pump working:

When you turn the key on, the fuel pump will run for 2 seconds (listen at the fuel cap with the fuel cap removed)

Check fuel pressure (38-46psi)

If pump runs and pressure is out replace fuel pressure regulator and the fuel filter (unfortunately, both are IN the fuel tank).
If pump doesn't run, troubleshoot pump.

Other causes from the manual:
Low compression (confirmed good)
Incorrect camshaft timing (unlikely)
Incorrect engine oil level (confirmed good)
Fuel contamination

Other speculation:
EGR valve?
EGR ports (won't cause it but can contribute).

 

Yes. all the warning lights illuminate at power-on prior to start and all turn of after the car starts.

I am the only one awake currently so i I went out early while it was quiet, opened the gas cap, rolled down the window and started the car, I did hear a kind of motorized whine for 1-2 seconds coming from the rear of the car. I can confirm when i my son is up.

I currently do not have a gauge to check the fuel pressure, however I found one online that i can pick up locally today.

The fuel filter and regulator are both under the backseat, correct?

I too have been thinking about the EGR valve. I would have to pull the garage work orders but I believe the valve was replaced last November, I do not know the make of it.
I was thinking it wouldn't hurt to clean it. What do you recommend cleaning it with?

The weirdest thing is that after we do something to the car (replace a part, fluids, etc.) I will test drive it and take the same roads every-time. Initially the car runs well but as soon as I get to the same point ( a local deli) that is when the power drastically deteriorates, almost as if a part that should be "kicking" in at that point is not, or if it is "kicking" in properly that that part is bad causing the issue. I hope this makes sense.

Since the car is showing no error codes the two garages I went to want a small fortune just to try and diagnose the problem, so thank you very much for replying.

 

If the EGR was replaced in November, cleaning is probably not needed.

If you're reading codes with a consumer grade reader, I recommend you take it to O'Reilly. Their Bosch code readers can read just about everything.

Per my post, both the filter and the regulator are in the tank.Tank must be dropped.

 

It was read at Autozone. We do not have an O’reilly by us, however I will call Napa and advanced auto to see what type of reader they have and if it’s Bosch.

When autozone read it we first had misfires in cylinders 1-4 which precipitated us changing the spark plugs and coils but was after the cat was replaced.

The reason why I too thought the EGR is the mechanic said that the cat blew apart/crumbled. I’m quite ignorant when it comes to cars so in my mind I pictured debris traveling throughout the car and it’s part thinking it was then clogging and/or blocking one of the sensors.

dropping the tank would probably be beyond our capabilities. So hopefully when I get the gauge and test the fuel pressure it will come back OK