Usually only dries the firs load

Hi,electric dryer will usually dry the first load, but after that, it shuts off too soon without drying the clothes,and no error code.It always gets hot but does not run long enough to dry. Disassembled and checked venting completely and ALL is clear. Once this problem starts, clothes will dry after repeated attempts but will not run a full cycle until possibly the next day. Thank You for any help!
UPDATE!! Checked thermal cut off,Hi limit t-stat and cleaned/scrubbed moisture sensor bars, all are ok. ran a load and it shut off before dry. Restarted cycle and watched timer count down, it started @ 52 mins, counted down to 41 mins then skipped to 21 mins, counted down to 19 mins then skipped to 15. At 14 mins it shut off and clothes still damp. Can I replace a cycle timer or is this part of the control board? Thanks again!