Loading up means at idle, in gear, for more than a few seconds and it starts missing out and there is an unburnt fuel smell in the exhaust. Like the old days when a carburated engine was choked or getting too much fuel. Don't know why it's happening to my fuel injected engine, but there has to be some reason. It's far worse in warmer weather, but now it's starting to do it in cool weather. Also does it sometimes on hot starts. Even when it's running normally, I can often smell that unburnt fuel odor in the exhaust. The fuel milage has not gone down very much, if any, but there is definitly a problem. Some things I have done recently:
Sprayed TB cleaner in the TB. It was filthy inside. No difference.
Drilled about ten 3/4" holes in the front of the airbox
New Napa Gold air filter
New plugs
new plug wires
new rotor and cap
new forward O2 sensor
fuel pressure checked. 38 lbs, but no leaking injectors.
Have a new fuel filter, but not installed yet.
Fuel pump was replaced about 2 years ago (50,000 miles back)