Alright guys, I searched but didn't find much about this... Anyway, it all started this last winter, probably about 4 months ago. I started my truck kinda late at night and drove about 20 miles away on the freeway. Early in my drive I noticed a really bad surging thing going on. I'd basically hold the gas pedal in one place (attempting to hold the rpms steady) and it would fluctuate up and down say from 2200-2300 RPMs. Since then it has not done it that badly, but it seems to really lack power, and then it'll surge, then lack it again, especially when it has been sitting overnight in the cold. I can't think of anything that would have caused it.

Anyway, it has gotten better over time but it's still there. For example, I was driving up a nearby canyon doing about 60 MPH... RPMs were holding around 3000 RPM maintaining speed but not wanting to go faster, when suddenly the engine would come to life and find some more power and I'd start accelerating, and then it would lose it again.

What could be going on? I talked to one guy that said that since I'm running a high-flow filter (Truflow) that it could be confusing the computer and so it doesn't know what the right air/fuel mixture is, but I don't buy it. I had been running that filter for a long time before this started happening. I replaced my spark plugs/wires last summer along with cleaning the MAF and throttle body, so I wouldn't think that they would be bad.

Any ideas?