Vehicle is 1991 Skyline GTS_4 A/T. This issue began about 2 months ago and was very random.....now it is predictable for the most part. Was driving home yesterday and Everytime I hit a bump or dip at any speed, the car loses power, then comes back online and continues as normal until the next bump....pulled into a parking lot from a near stop and the car actually stalled out and died. Here is what I have installed chasing this...New splitfire coils and plugs, new OEM ignitor, new OEM MAF, New OEM CAS and also replaced my Walbro fuel pump with a new AEM pump. Nothing has fixed the issue....any ideas or things for my to try?

Loose grounds or bad wiring come to mind. Maybe try getting the car in idle with hood popped, then jiggle the engine harness in a few locations and see if you can get it to stumble. Same goes for turbo systems, but with the vacuum. Try car in idle, hood popped, and jiggle the air plumbing you may have to see if the engine stumbles.

The GTR pros will see this and maybe have some better ideas. Good luck!

It was the battery ...connection problem of post inside the battery.

Inside the battery? Weird. Glad it's sorted out. How'd you spot that? Tugging on the cables or during a disconnect?