[FIXEd] 2003 Jaguar s-type 2.5l V6 petrol with sluggish performance

Hi SD world,

This vehicle came to me originally for harsh transmission shifts. Road test revealed very poor performance requiring a higher than normal throttle opening to maintain speed resulting in harsh shifts. DTC's relating to O2 sensor heater circuits on all but one (bank1 upstream) open/short. Test remaining sensors found heater circuits open replaced sensors. With engine running checked for vacuum leaks with small amount of propane and idle note changed indicating leaking. Customer was unsure when then spark plugs were last replaced so plugs were removed and inspected at the same time as replacing manifold seals. Cam cover gaskets were also replaced due to large amount of oil in plug holes. New spark plugs were along with 3 ignition coils due to oil damage. Re-assembled vehicle cleared codes, disconnected battery for 15 minutes joined + to - , to ensure learned parameters cleared.

Roadtest vehicle found to have improved but still not performing properly. Checked fuel pressure 375kPa increasing with load checked pump stall @ 500 kPa fuel filter was replaced as a precaution, wasn't able to check flow of the returnless system. Checked exhaust back pressure 0kPa with minimal increase on acceleration. I have tried to clean the Air flow sensor with no improvement although I suspect this could be the problem. With the sensor disconnected the engine revs much better (assume base values are substituted in) I haven't been able to find reliable information for pinouts for the sensor. I've only been able to determine battery voltage and reference voltage are present. Grounds appear to be ok. Battery voltage to the centre pin shows voltage variation when the engine is accelerated but doesn't correspond to any information I have on hand,

Ideas would be appreciated, TIA,

Rob

Update,
Faulty MAF , managed to find a known good vehicle. Swapped MAF , vehicle performs normally. Install new part, vehicle fixed.