My buddy has a 2004 Ford F150 with a 5.4 L V-8 engine, a little over 100,000 miles. The engine started running poorly and we figured out the passenger-side phaser went bad. While we were in there we replaced both phasers, the timing chains, chain guides, and the belt tensioners.

Started the motor and it ran perfectly. He let it idle for a while to get it all up to temp, and then took it for a drive around The block to check it out. About halfway around the block the engine started running horribly and had no power. He pulled it back in the garage. We figured either we had gotten the timing incorrect or somehow it had slipped a tooth on the chain. Once the motor had cooled down, we took it back apart. We checked the timing and it was exactly how we had set it. The only code is P2196, "stuck rich bank 1". Had it towed to dealer, they said the timing is 55 degrees off at idle...but if you rev the engine the timing adjusts and is fine. The phaser apparently has a 60 degree adjustment range. Suggestion is engine repalcement due to cost of taking everything back apart and trying to find out what's going on.

Any ideas?