No vacuum leak that I can see.... Whats the next thing to check?

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2004 Ford F150 Automatic FX4 SuperCrew 5.4L 3V Triton V8, No Muffler, true dual straight pipes, 3.73 Gears, 18" rims with Wrangler A/T's
White 2004 Ford Ranger XL, Auto, 4.0 SOHC, 4x4 Base Model, 16" Explorer Rims. 3.73 Gears, No muffler(Sold)
White 1997 Ford Expedition XLT 3inch Suspension lift, 38 Firestone M/T's 98 4.6L Police Interceptor high flow injectors, Super 44, brand new rebuilt transmission, with 3.73 gears(Not mine no more)