Slip Or Shudder In Forward Position After Warm-Up
WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
Check upper valve body, oil strainer, torque converter clutch, forward clutch, direct clutch, underdrive brake, No. 1 one-way clutch and underdrive clutch.