Odd idle issue

[harold]

So, since I swapped the new engine in, I've been having an odd idle problem. If I'm driving and depress the clutch pedal, the engine will race to between 2k and 4k (seems pretty random). The problem is worse when it's warm. The thing I noticed today is that if the car is going under 10mph (as reported by the ECU through the ODBII port, not the speedo), it'll drop pretty quickly. Once it drops, it'll still be a fairly high idle (1100-1300 usually), but nowhere near as bad as when I'm moving faster than 10mph. It doesn't matter if I use the brakes to slow below 10mph or just coast there, so I don't think it's a brake booster leak.

I was originally thinking it was the IAC, but if the speed is influencing it, I'm at a bit of a loss. I used the intake manifold that came with the engine I got from Al and I was thinking of swapping my old one on there to see if that makes a difference. I won't get a chance to do that for a while, though. I was considering doing some datalogging with my XCal2, but I'm not sure what would be best to log. Is this a common problem?

[Steve@Tasca]

TP sensor? Are you using yours or the used one?

Was the used engine from an auto or manual? I forget.

If you used the intake and TB from the used engine and it was an auto then you have the wrong tp sensor on the car rigth now.

Thats my only guess.

[harold]

Sorry, forgot to mention that it had the manifold, but not the TB. It was from a manual car anyway, but I've got the same TPS that was on my car before. Al did mention that there was an aftermarket TB on there, but I didn't notice any difference in the shape of the port at the TB flange when I swapped the TB onto that intake, so I don't think it's sucking air through the bypass when it's not supposed to unless the gasket isn't sealing. Are the TB gaskets reusable?