Advice sought - engine flush with NO oil change

[MyYeti]

Evening all,

I have a Mondeo V6, when I last had my MOT done, Kwikfit put in some "engine flush" to get it past MOT, which I have only just now realised when checking the receipt.

I have not really used the car, but it has been there since September 2015 and driven for 1000 miles (or less).

Now, having been trying to figure out why the engine would not rev past 4000 rpm (not limited because it is in "Park" on the auto) when driving, it revs fine below 4000 rpm, but once reach 4000 rpm it runs like a dog, after checking almost everything (EGR / MAF / Lambda) I think I have reached the conclusion that it's probably the sludge that was dislodged and now stuck somewhere...

Question is, what can I do? I intend to get the oil change ASAP (and don't drive it, can drive the other car), should I add some additional "engine flush" like Wynn's into the system before the change and hoping the sludge will be dislodged from some injection components or chain...

I am partly to blame I guess, but surely anyone who can speak should have warned me about it after the MOT about changing the oil ASAP (let alone I paid for the damn MOT and is a customer!)

Many Thanks!

[MyYeti]

I am thinking sludge and the cam? I could be wrong...

The problem is when I visited a garage a couple of weeks ago, it shows no fault code, so nothing to fix, according to them...(not Kwikfit this time!)

[MyYeti]

Thanks for the reply. I will take it to another garage as the first one just said its fine...

Reason why I mention Park is because there is a limiter at 4000 rpm on this car in Park.

The car was service prior to the MOT so the oil is clean.

As you mention it, it does burble and does sound like the exhaust is going, could be the cat.

[MyYeti]

Thanks - another garage says the cat is completely clocked and is a mess, so that will now get changed!