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Hey guys, I have a 93 turbo FD, so the problem is when i go to start the car it goes up to 4k rpm and then drops back to 2k rpm but the whole car rumbles like an earthquake when it does. Also when i went out for a drive to test it i feel a ridiculous lack of power and the car stops revving at 4k rpm. At 4k rpm its starts to sort of sputter and the revving becomes erratic. Cant really slam on the gas either, you have to go softly like at 40% throttle. Any ideas what could be wrong?

Before i realized that spark plugs were shot, i replaced them. Car works a little better but still has the same behavior.

Fd3BOOST

I'm pretty rusty since I've been out of the game for at least five years but I would check the Throttle position sensor (TPS).