Check the connection to the auto tranny ECU under the kick panel on the passenger side. If it's not seated perfectly it can cause the trans to freak out. The connector should be completely seated and the bolt holding it snug but not tight. A light spray of dielectric silicone lube also helps.

You should also check the trans ECU for trouble codes.

Definitely do the swap to 5 speed it's well worth the trouble.

Check the classifieds at twinturbo.net for the pedals