Engine Idles Rough on 2002 Ford F-150

02' F-150 Sport 2WD Triton V8 4.6L COP's. Rough Idle. In drive or park. Symptom appeared immediately. Check engine soon light came on 2 days later (not blinking). Often lose power...normal breaking into a turn, lights dim, brake power dies, steering tight. Some bucking/spitting while gradually accelerating out of turn. Increase acceleration swiftly and she smooths out and gets up a little, but still notice weakness in power. Also cruising at 55, let off gas and she'll hold rpm for 10-15 sec and then deccelerate as it should when I took foot off. Local mechanic doesn't know. Already tried Mass air flow and Idle air control sensors. Could this be vaccum leak or throttle position sensor?

by in Carlisle, PA on October 20, 2010
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2 answers 2 comments
ANSWER by , October 20, 2010
What codes where registered in the ECM when they scanned the system? The throttle assembly might need some cleaning. I'd also check the EGR valve, make sure it's not keep stuck in the open position. Zee
COMMENT by , October 24, 2010
Thank you. I'll try those next. Truck has 108,000 miles. Time for indepth maintenence.
ANSWER by , October 20, 2010
I'm thinking you could also have a fuel control or supply issue. Just a hunch until you get the codes out of the processor, as Zee said.
COMMENT by , October 24, 2010
Thank you. The local mechanic said there were multiple codes. I should have had him write them down for me. I'll get the codes again. Maybe I'll invest in a scanner.