Re: 93 F-250 460
Does this happen in overdrive, direct drive (1:1, generally third gear), or both?
It could be something as simple as a vacuum leak. Worst case would be a transmission problem. Is the engine light on? If so, be sure to have it scanned for the codes and post'm here.
Any more info on the 'hiss' sound would be beneficial for myself, and others to help diagnose.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!