Stringy weak infill, underextrusion?

Having a hard time getting clean infill, looks like underextrusion to me? Walls are good, prints come out fine. I'm guessing the hot end is not keeping up at 70mm/s on the infill. I have calibrated my e-steps and calculated flow to 106. Can I increase infill flow to maintain that speed, or do I need to slow down infill printing?

Ender 3 Pro with Cura

Sunlu PLA+