Is this an old shape Sorento or new? The information below relates to old shape:

Are you sure it's a misfire? Or is it the 4wd system locking up between 30-45mph....


If it's got AUTO on the 4wd selector switch, it's more likely to be the torque on demand system transferring power to the front wheels under load, and an issue is causing a "shunt" type feel when driving.
To confirm the fault, once started remove F14 (TCCS) and roadtest (note this is also an immobiliser fuse so may not start if removed Key on/engine off)

If the fault has gone:
All tyres must be the same rolling cirumference, any difference of more than 2mm in tread will cause symptoms.
Remove the front propshaft and make sure the sliding joint is free.
Check Transfer box fluid level is correct manual states Dexron 111 but I'm sure they've introduced a special T.O.D oil for these now....

Check axle levels and backlash 3-15mm is acceptable at driveflange.
Check no brakes are binding, especially after roadtest.

If all of the above don't cure it, a new clutch pack inside the transfer case may fix it, but after several issues we now only fit a complete unit.
I have a test sheet for these if you want, I can email it later.

Tony