I am just finishing up an M50 swap but I am having a weird issue. Under constant throttle it drops in RPM then bounces back and keeps doing this repetitively. It only happens at lower RPM/throttle position. It idles fine and at higher RPMs it runs great. I have swapped MAFs, TPS, O2 sensors, and checked for vacuum leaks. Does anyone have any ideas on what could be causing this? The engine is an M50b25tu out of an E36. Attached is a video of it running. We are slowly increasing RPMs throughout the clip.
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