1994 XJ12 - The car never starts right away, always need a few tries unless I turn the key in position 2, let it sit, go back to 1 and crank it.

Both ignition coils have been changed as well as ignition sensor and all 3 belts are new + battery. Fuel pumps are good.
Furthermore, car totally loses power in sharp turns (never stalls) and there is a great chance there is something wrong with the exhaust but the mechanics seem to ignore that option.
I know the ignition and fuel systems are complicated ones, what could it be???

Is there any exhaust cleaning procedure recommended beside common additives?

 

thanks - will check it and I will replace the fuel filter as well - might help