Engine Bogs Under Load

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i have 1998 sierra 1500 4x4 ext cab with the 5.7l vortec engine, engine intermitently bogs sometimes when you take off or are pulling a trailer, its like nothing is happening when you push the gas pedal- engine does not rev up for a 10-15 sec period. you can let off the accelerator and on it and off it and then out of the blue it will ignite and lots of power, the throttle positon sensor seems to be working, checked fuel pressure at stainless lines and have 55-60 lbs pressure, fuel filter has been changed. no engine light on but scanner is reading a p0453 code, which i belive is the fuel tank sensor code saying that the pressure is too high. i was going to change the fuel pressure regulator but the pressure on the lines seems to be ok. any ideas would be greatly apprecitated, i am extremely frustrated and have been trying to figure this out for some time now and am running out of ideas to try. thanks for your help.