i recently bought a 2003 jag str with 130k miles it’s been sitting for over 2 years replaced fuel pump and changed the oil and the fuel filter but the car turns on and runs fine but everytime i rev the engine the car stutters and chokes out like if it was misfiring all the coil packs are working, new spark plugs the car doesn’t shake or anything when it’s in park not throwing any misfiring codes i can feel and loss of power when i try and step on it because it chokes out when i try and step on it

 

Did you replace the old fuel or just the pump

 

Just the fuel pump i should’ve vacuumed all the old fuel out. i put fuel additive in it yesterday and filled the tank up but its still doing the same

 

Do you have a scanner? What is the value shown for fuel pressure?

 

Did you use the correct pumps? There are two and they are different from the non SC cars. At full throttle the second one kicks in around 3000-3500 rpm. Is this the range your having problems?
What is your fuel pressure? There is a test port on the passenger side rear of the engine. If you have no gauge you can read the pressure with some scanners.
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As above mentioned old fuel could be the issue. Fuel in general starts to get old after 3 month.
I do not trust additives of any kind.
I once realized that the fuel pump was dead on my Fairlane, which runs on LPG (= gas as in gas for cooking), but the system still uses petrol from the tank during start-up and then switches over to LPG. This meant, that the petrol in the tank got very old over time and it "came down" as a gluey substance on the tiny moving parts of the fuel pump - which is why I replaced the pump. But about 10 minutes later the Fairlane again did not run anymore...: The brand new fuel pump was dead again - again destroyed by that gluey stuff in the fuel...!

Other than than that, my recent standard answer to all problems could also apply to you - it's an easy check, which does not cost anything:
Check the connector for the throttle body butterfly motor under the rubber air intake...:
https://www.jaguarforums.com/forum/s...nector-288221/