Does a vr6 vw jetta motor fit into a 1999 vw passat?

No, it will not fit. No exceptions. The only V6 engine that fits in the B5 and B5.5, is the 2.8 V6 AHA Audi/VW engine. The VR6 is transverse mounted, the 2.8 V6 is longitudinally mounted. The Passat's transmission will not mate with the VR6, and the electrical and OBD II is totally different.