97' 5.4L power loss?

[bulrid8]

Hey guys,
Tried searching but not finding answer.

Truck will run great, then lose power. Then come back like a switch being flicked on. Will do it at idle or while driving. Only time it does not do it is if running above 85mph.

Did have egr code, but replaced sensor and that code is gone. Only code left is bank one o2 sensor. Will an o2 sensor cause that much power lose? It acts like it loses half its power.

Plugs and all cops were changed last year.

Any ideas?

Thanks

Sent from the all knowing box!

 

[Jeff532003]

Did you replace the egr valve and clean the ports in the throttle body spacer as well? The commonly get plugged up. Ford recommends a new egr every 80k it memory serves me correctly. Could also possibly be an O2 as they set the lean rich mixture but I've never heard of one causing that kind of issue. I'd check around for a vacuum leak first. Start with the rubber elbow that is on he pcv tube behind the top of the intake. It's a known issue. Also the vacuum lines from the egr tube up to the sensor are known to go bad as well.
Hopefully someone else can give you some more definitive advice as to what it may be but I've never dealt with this issue and its hard to diagnose over the Internet. Good luck!

 

[BANGEREXPO76]

Yes a bad O2 sensor can cause those problems.
If your getting a code. I recommend changing the O2 sensors.

 

[bulrid8]

Thanks guys.
Planned on replacing it, just never seen an o2 sensor cut half power on and off. Usually just kills mpg some.

Sent from the all knowing box!

 

[cavakilla]

Check fuel pressure while driving...