Loss of power

[heatst]

I have a problem with loss of power under a load. The car pulsates, surges and loses power under acceleration on inclines on the highway. You can not pull out into traffic either under moderate, or heavy aceleration. When this happens sometimes the engine revs and the rearend feels like it locks and un locks and chrips the tires. Had to the dealership no codes, no help from them. It just not safe pulling into traffic when it does this. If you stomp it from any speed or dead stop it does it. any help would be great. It is a 2006 AWD Mountaineer.

 

[YamahaBill]

Mine had a miss at low RPM in the higher gears and changing the plugs solved it. It felt like a jerking feeling or a chug. It didn't bring any codes in either because from what I've heard the ECU can only detect a misfire if the coil is malfunctioning.

How many miles on the plugs? V8?

 

[heatst]

25,000

 

[YamahaBill]

25,000

mehh seems too early but you never know. Rated for 100,000 miles and they had 55,000 on them when I replaced them.

 

[heatst]

I changed all eight spark plugs and now it works. I don't get it. I really thought it was the transmission and so did the dealership. Thanks to you guys it works.