Poor acceleration at low engine speeds

Hi peeps!

Newby to micra scene, had a small ldv but A14 engine (not related I know!)

I was searching for hours already on here today,
Found only one possibility, so of I missed something please direct me,

we bought a K12 1.4 what I could gather from the license disk, with 145k km on the clock, 1 owner.
First of all the terrible oil leaks, I fixed a couple of possibilities without removing the gearbox, it seems there’s a major seepage from the crank seal, also sitting at traffic lights and pulling away when you floor her she smokes something crazy, but not at first start up,

The latest one afternoon I had an doctors appointment and starting the midget, I experienced a weak acceleration at low throttle position, but if you put foot to the floor it seems to disappear ,
Someone suggested removing the cat should solve the problem, but alas not at all!

Went to church the other day, with me driving I noticed the poor acceleration again, same as before,
I am furious at this midget already 😜
Just some background info, when we got her I serviced her, cleaned the throttle body before replacing the intake box thingy,
Replaced crank seal at left side which I could reach while replacing the water pump that was noisy !
Checked and double checked even triple checked the spark plugs and coils after a few 100 kms!

I am not a newby when working On cars, let’s say I can help myself around the engine bay,
But the micra…. Another story for another day!

Any ideas? ….except for the thermostat that I found suggestion to on this forum?

Keep in mind if you go over the 4k rpms the vehicle will do something to avoid over revving.
Rev limiter I think it's called.
Also check the ground points if you have not already.
Main thing is keep looking, see what others have to say. I'm just a newbie still. But recon the ground points are worth a look.
Poor acceleration you can start by replacing the air filter and put some petrol additive into the petrol to help boost the performance and clean out any build up of carbon that could be clogging up the valves and pistons the smoke you describe when accellerating is it blue or white smoke?
Could the clutch be slipping if there's oil leaking out the seal?

It could be they way it's written, but almost all cars have poor acceleration if you only lifhtly press the accelerator, and will go faster if you press it more.