Flashing D light, tansmission goes out then back in??

your vehicle is going into limp mode with a transmission issue have it checked for codes that are stored could be a sensor issue

This sounds like a Speed Sensor Issue, check the code. But more so of, it seems more like a speed sensor, it's quite a pricey part and can sometimes be hard to replace if you don't properly do it right with the gasket piece as well.

I needed a new 2nd clutch transmission pressure fluid switch how do i get the engine light to go off

Mine is doing the same thing how expensive will it be??