Originally Posted by Bell Blue Raider
my 99 4.6 does the same thing, but it's kind of odd. it only does it at night, if it does it during the day time then all i do is check cylinders 3 and 4 for antifreeze and check the coolant hose over cylinder 4 and try to see if it's loose and that fixes it during the day time. the same fix doesn't work at night though so i'm starting to think my truck is just afraid of the dark.... i'm going to check my passenger side plugs here soon and also trying to change my exhaust manifold so hopefully that's the problem with mine
lol, to funny about truck being afraid of the dark
All these vehicals with this issue, is each current with maintinance? Fuel filter, plugs, wires, filters, PCV?
When plug wires begin to break down, (especially as they heat up from driving) you will loose spark. Also on these vehicals, 97 & above, Ford gets more & more technical with each, (sensors wise), and something as simple as a dirty breather filter will or can **** um up side ah ways, (make um run chitty).
Oxygen sensors as well as they begin to reach their max life. If you have over 50 or 60,000 miles on the engine may be worth changing them out before they offer codes.
We all have become spoiled to some degree with the CEL invention. If no light on, we can go without doing maintinance, more time to drink beer on Saturdays,
And the ole saying if it aint broke, don;t fix er. Another saying is fix er before it breaks & leaves ya on the road side! lol
With no CEL on this is what I try to pay attention to as I drive.
Typically a vacuum leak will increase or kill your idle as well as make for some rough running engine when loaded.
Electrical, (plugs, sensors, wires, ect) will sputter under load, (as described in some above post), if from wear, it will begin gradual & become worst as the part becomes worst from wear.
Fuel filter, air filter, MAF, will cause rough idle, worst when loaded, & even more worst when increasing the load such as giving it more gas.
In addition, I review my records to see if it is time for any maintinance.
Hope this offers some help, if not, bac to drinking that beer