Hello and thanks ahead of time.I have a 94 civic that runs like a top as long as you keep the automatic trans from going into 4th gear overdrive.It will run all day long and not skip a beat in 3rd.But,the second you let it go into 4th gear overdrive,its like the key is shut off.The car acts as if brakes are applied,misfires, and dies.If you shift it back into 3rd while this is happening it straightens right up and runs great.Please help.Going crazy.Seems abit gas fumey as well.And oh yes,it seems to do it more often if the fuel tank is fuller.

 

Get your fuel pump, egr checked out, could be a improper fuel mixture causing it to misfire and can cause it to run rough, possible the cause of the gas odor you're talking about