Spray 4- to 5-quart slow cooker with cooking spray. In small bowl, mix chili pepper powder, oil and salt. Rub mixture over pork; place in cooker. Sprinkle with poblano chile. Pour salsa over top.
Cover; cook on Low heat setting 8 to 10 hours.
Remove pork from cooker; place on cutting board. Shred pork with 2 forks; return to cooker and mix well.
Using slotted spoon, spoon about 1/2 cup pork mixture onto each tortilla; top with about 1 tablespoon each guacamole and sour cream. Fold one side of tortilla up about 1 inch over filling; fold right and left sides over folded end, overlapping. Fold remaining end down.