Poor running P38 4.6 v8 after Wading

Hi, Can any one help?, spent day off roading with no problems until last flood, powered through flood and got through ok, engine stuttered after 100 metres lost power, regained power for moment then lost it, got on road with on/off power to 45mph first hills down to under 20mph, continued to drive for few miles, stoped at Services. Air filter was wet, removed it and cleaned air box. Engine starts and sounded smooth on tickover but wouldnt rev with full power. Continued to drive for few miles got worse, stoped and noticed LH Cat was glowing bright red, got home on tow rope. Next day checked plugs, full spark on all, runs with no knocks or vibrations but wont rev past 2-3000rpm. Has anyone go any ideas ??? Air flow meter? Lambda sensor? cat?