I have a 2000 f150 2wd. Started having no power issues all of a sudden. Thought it was the cam tensioners sense they had never been replaced. so I replaced them. old one's were bad. I also upgraded the cam to a comp cam. not very large. still have same issues. have changed fuel injectors, coils, throttle body. tps sensor. there are times when I start it it will burn the tires while holding the brake. other times with the pedal all the way to the floor it will not go over 2000 rpm.

 

Is the CEL/SES light on? Any codes? Must be a 4.6 or 5.4.

Sounds like you're saying that sometimes it runs right, and sometimes it doesn't.

We used to call burning the tires with the brake on power-braking. Not sure why a person would do that when they start it though. The no power with the pedal to the floor sounds like one of the fail-safe modes. Engine too hot, or transmission range sensor not working right.

Add more actual details about the engine, transmission, parts and behavior (of the engine). All you've really written is "2000 2WD F150 with a bunch of aftermarket parts".

 

Welcome!
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Vehicle Information Engine? Miles? Modifications? (other than cam)
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One generic code. EGR insufficient flow. Engine 5.4. Only changes that have been made were posted below. Transmission is factory stock. Differential is factory stock. No other codes. Yes sometimes it runs right and other times it doesn't. This is noticed while normal driving. engine at operating temperature. There's no engine temperature issue noticed.

 

Have you pulled the upper intake manifold and cleaned out the carbon? Likely clogged egr ports or a sticking egr valve. Might want to clean all of the sensors and valves attached to the manifold while you have it off.