Search for 4Crawlers procedure on setting the TPS to spec. Your problem sounds like what I went through after the first head swap. Code 51 would pop up as soon as the engine was started. Cruising down the highway I could hear/feel it miss when holding steady RPMs...once I learned how to set the TPS to the sweetspot the problem was solved.

On your AirFlowMeter, unless you've messed with it or been in an accident where that corner was hit hard....chances are there is nothing wrong with it. They rarely if ever just go bad. Give the garage the finger unless they wanna cover the parts they are gonna throw at it.

~Darin <img src="/forums/images/graemlins/baby.gif" alt="" />