this morning I went to go to work and starting the car it reved really high I thought nothing of it but as i drove down the street i noticed it was lgging a bit and the engine sounded muffled it sounds like it sucks in air from exhaust pipe but not sure .
I did oil and filter change about 2 months ago
I am really stuck as to wat it can beeen

the car is a tj wagoon on gas and petrol auto !

Check spark plug leads. You may have a misfire. Need more info though, like what does "lgging" mean?

lagging sorry !and feels like its lost power and not as responsive

So, revs really high on start up? (How high?)
And can you get a video of this and post it up?

only reved high this morning at just under 2

Perhaps one of your plug leads has come off the spark plug, or has oil on the spark plug. Have a look.

rac came the muffler is stuffed blocked baffle restricting air flow

Pretty normal. There's a director in the union of the header banks that likes to dislodge and block the cat too. When you fix it it's good for another 80kwatw ;)