So I’ve started this thread because I couldn’t find one about any similar problem, I have a 90 Supra with the 7mgte and everytime I reach 5th gear and get to 4krs my car dies and my rpm gauges drop to 0 this has happened twice and I want to know what it means

Recently rebuilt the top end of my 89 Supra Turbo starting from the head gasket up. As of now the car has a very strong idle and starts with very little drama and with no assistance from the throttle. The issue arises when you try to give it some rpm in neutral. The car will not react for about...