I have fuel coming out from under the engine when I have a cold start. Is there a fix for this? I also am getting very poor fuel economy. Please help

Go to local auto parts store and they scan it for free,possibly heads or coils,check it or post codes

The idle air control valve is designed to adjust for the load on the engine to maintain the idle quality. When it's cold out, it's more important that the engine temperature sensor is working correctly so that it can trim the fuel richer to compensate for the cold running conditions. Also, a dirty Mass Air Flow sensor could give you problems with your idle. A shop could easily diagnose the poor idle quality for a reasonable fee if you don't feel like throwing parts at it again. Have you experienced unusually poor fuel economy or better than normal fuel economy this winter?

Lead foot, tire pressures, stop /go driving. AC/poor compression, Trunk full of sandbags, transmission slipping, Wheel bearing friction, Brake shoe always on, etc.

I would check the coil those wires are probably on the same coil

Is the check engine light on? Do you have the tire pressure up to spec pressure? Are you using the correct weight of engine oil? Do you accelerate like an egg is under the gas pedal?

Poor fuel economy can come from bad fuel or tune up.Try switching to a gas with a higher octane and give your truck a full tune up.This should help your fuel economy out a little.

Sounds like you might have an oxygen sensor problem. Your catalytic converter(s) maybe defective or dirty. That in turn can dirty up the oxygen sensor. A defective oxygen sensor will send faulty info to the computer, interpreting the fumes as cold (even when the engine warms up). That causes the computer to adjust the fuel mixture to very rich, giving you poor gas mileage and the fuel smell. Hope it helps.

check for a bad fuel pressure regulator. a bad regulator can cause:hard starting, poor fuel economy, stalling, check engine light on and a gas smell under hood.

the "rattle" will be detonation caused by spontaneous combustion from incorrect air/fuel ratio and incorrect ignition timing
it is most prominent under acceleration or under load ( up hills , high speeds etc) and will melt pistons if left unattended
run the fault codes to find the faulty sensors , but I suspect that the heated oxygen sensors(HO2S) in the exhaust manifolds before the cat converters will be at fault as they report the gas composition back to the ECM so that the mixture can be adjusted correctly ( indicated by the poor economy)
there are knock sensors on the block which are indicated as faulty as they should be reporting this condition to the ECM to adjust the settings
finally it could come down to low fuel pressure or faulty injectors
what ever it is you need to get a proper fault code reading and have the problem fixed asap as it will cause engine damage if not fixed