With the engine off how much pressure should I expect at the fuel rail? And how long should it hold pressure (if at all)?

Car was starting hard and stumbling on acceleration. Main fuel pump was noisy so I replaced it with a new Bosch unit. Have 31 PSI running and 40 PSI running with the vacuum hose disconnected from the FPR. When shut off the pressure drops to around 24 PSI then bleeds down to 10 PSI after 10 min or so. Starts and idles fair but not like my other 240's. Goes down the road fine.

FPR was also new and I have tried two other known good FPR's with same pressure results. Could the injectors be leaking by? 260,000 on the car and only have replaced normal wear items (belts, hoses, oil, and 1 water pump).

As for the starting and idle I also swapped out the AMM with a know good one, cleaned the throttle body and idle motor, new O2 sensor, replaced all vacuum lines, flame trap, fuel and air filter, intake gasket, and intake hoses are good. Wire harness was done long ago.

In-tank pump appears to deliver a good flow of fuel, runs quite, and the car will run below 1/4 tank.

Thanks for any information.

Mike
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1984-244 GL, 1985-244 DL, 1985-245 DL, 1989-244 DL, 1989-760 Turbo, 1967 Mustang (271 HP 289) and 62 F-250 4x4 (262 - 6 cylinder)