Surging rpms at Idle

[73cntry]

I have a 04 F-150 supercab Heritage with the 4.2, everyday the engine surges and one day the truck shook while sitting at a stop sign. So I didn't step on the gas and just let it work itself out which didn't take long.
The engine has 75,700 miles on it, and was wondering what can cause this. The fuel filter was changed at 70k still has original plugs and wires.
Any help is welcomed!!

[BrianA]

Originally Posted by 73cntry

The engine has 75,700 miles on it, still has original plugs and wires.

Well, there you go.
That'd be my first step.

Plugs and wires have been proven to:
a) last about 75,000 miles
and
b) cause surging, erratic idle, etc.

I always suggest sticking w/ Motorcraft when it comes to plugs and wires.

They can be bought for less than what the dealer typically charges.

[73cntry]

Thank you for a quick reply!!!
That's a good thing I picked up some motorcraft wires today at the dealer which was actually cheaper than Advance Auto. Now just have to get spark plugs. Motorcraft is better than autolite plugs, or Bosch etc...