OBD2 S14 acting crazy, help

[rim_bender]

Im trygin to help my freind fix his car. It's a 1996 S14 so its OBD2 and an automatic.

two issues:

One, when you start out from a stop and floor it, it feels like it has no power at all, or seems like it alwasys starts in 2nd gear, cause as soon as it gets up in the rpms it starts to pull like it should.

Second, the idle is crazy, it idles up and down constantly between 300-600 rpms and almost shuts off sometimes.

The car thew three codes, knock sensor, vehicle speed sensor, and intake air temp sensor

The gear on teh speed sensor is chewed up so it wasnt even turning, so the speedo is not working. Could this be why the tranny starts in 2nd maybe?

the intake air temp sensor was swapepd with a kown good one.

All the codes were reset and the CEL has not come back on, but the car sill idles super bad and it still feels like it has no power down low or it starts in 2nd gear.

What could be wrong making the car do those two things?
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