Car not running right while cruising!

[iambatman]

Ok so my car is a 91 240sx hatch. I just put a sr20det in it. The motor is stock besides fuel pump, t28 turbo from s15 and intercooler, radiator exhaust the usual. The cars starts and idles fine I can rev it, hold it at any rpm and it runs just fine. Now here is the problem when Im driving and just cruising and barely giving it gas the car acts as though im pushing in the gas then letting go, then pushing in the gas then letting go. It does it at any rpm in any gear as long as im not either flooring it or giving it over 25 percent throttle like accelerating. It only does it while driving not while not moving or anything just when im trying to maintain a constant speed while driving i have posted some videos listen to the engine throttling on and off. Thats not me moving my foot on the gas at all I leave it in the same spot and it cuts off and on, on its own. PLEASE HELP! Also I have a Walbro 255 fuel pump. Remember car runs like a champ when hard on the gas! Just not when I'm trying to do the speed limit.

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[ultimateirving]

Get a new fuel pump with that SR,

edit: misread, Stock EXCEPT fuel pump.

The term for going faster/slower is called surging. Try searching (surging while cruis*)

[iambatman]

I have a Walbro 255 sorry did not mention that!

[iambatman]

searched and only seemed to find surging problems while idling, my car runs just fine at idling! Anybody chime in??