2005 Suburban Transmission Question
 

2005 Suburban 5.3 L, 4L60E, 4WD 245k miles
Truck felt sluggish Friday afternoon from cold start. Realized it was taking off in 2nd gear, not 1st. Shifting manually to 1st would not activate 1st gear. After driving a few minutes first gear returns, Transmission shifts smooth, normal operation otherwise. Serviced at regular suggested intervals.
Solenoid problem? Your input appreciated as always, Thanks!

Update - In last 10 days has recurred at cold start 3 more times. Took to mechanic, left overnight so he could see cold start and of course, worked fine. No codes found, fluid pink and happy and last serviced 20k miles ago. Will wait and see!