Got a 1991 EFI 5.0 with the H.O. mod and at all different engine speeds the engine seems to sporadicaly miss or as some others say surge. It idles smooth. It happens sometimes for 1 or 2 seconds and then may not happen again for many minutes. Sometimes its just one miss sometimes several in a row. Feels like the key was turned off for a split second. Mostly noticeable at lower RPMs. Seems to clear up at higher RPMs. Been through all the basics, cap, rotor, plugs, timing at 10 and steady, fuel filter, vacume steady at 20", fuel pressure steady at 29psi and 39psi with regulator disconnected, no codes showing, cylinder balance test OK. I'm leaning towards an electrical problem but open to all sugestions.

 

I had this kind of problem with my wife's 1990 crown vic know one could figer it out . THe car died a few times in a intersection it turn out to be thedistributor I had a parts car so it cost me nothing and it fix it hope this helps/


reman519

 

I had that problem with a Chevy once. It turned out to be some electronic part in the transmission. Come to think of it, my 2003 Mercury Grand Marquis' engine did "miss" while stopped at a light recently, but the engine was knocking whenever it would shift gears too. The torque converter was bad. Is there a connection? Don't know, but it's probably worth looking towards the transmission and its electronic controls, if any.