I have a 91 5.0 with the E40D tranny when I start the engine it will rev up to 1500 rpm then fall off to 1000 rpm then pick back up to 1500 rpm. When I unhook the vacum line to the fuel pressure regulator it starts just fine. I've replaced the fuel pump, regulator, tank, IAC, TPS, MAP, and O2 sensor. It does this no matter which tank I use. I have 38 lbs of pressure with vacum line hooked up 44lbs without. Checked for codes got 111's across the board.Thanks for all help in advance.

 

Mine does the samething... Except it goes up to about 2000 and wont go down till I touch the gas pedal