What was found
AUTO THROTTLE DISENGAGED AND WILL NOT RE-ENGAGE. GROUNDED - YES. RELEASED PER MEL 22-4B AUTO THROTTLE SYSTEM INOP. ACCOMPLISHED A/T SYSTEM TEST REF B737-800 AMM 22-31-00-710-802. ALL TESTS PASSED. DUE TO FAULT HISTORY, REMOVED & REPLACED FCC-A REF AMM 22-11-33/401. ACCOMPLISHED DFCS LRU REPLACEMENT TEST FOR FCC REF AMM 22-11-33/401. ALL TESTS PASSED. ACCOMP LAND VERIFY TEST REF AMM 22-11-00/201. ALL TESTS PASSED. THIS CLEARS MEL 22-4B & 22-99B. GROUND VERIFICATION SUCCESSFUL.