1996 Dodge Ram 'pop pop pop' when under accelearation HUGE

Greetings,
I've a Dodge Ram1500 V6 with under 100,000 miles and appeares in pretty good shape overall.
However it has a 35 gallon fuel tank and the truck can empty that in just over 350 miles without too much strain.
When the vehicle first starts it lacks power to the max. It hardly goes up the hill, and under any kind of 'pull' it pop pop pops (not exhaust but intake) 'backfarts'.
Fuel comsumption is horrendous.
Changed the plugs, no avail. The Check engine light comes on shooting codes of 43 (other than 12 (batttery disconnect) and 55 (end all codes). The 43 code repeats sometimes. I recognize that there is 'random engine misfire', but where do I look to correct this?
What do I check?
I need to use this truck to pull a car, but the truck can hardly pull itself.
When this is finally solved, what kind of milage can I reasonably expect from a V6 (3.9 Litre) automatic Ram 1500?
Thanks in advance for your assistance.
More information forthcoming as you dealve into this mess.
Jerijan