ABS is most likely the front wheel sensors, VERY common, where they go into the hub they get rusty. The sensor is pushed up (rust expands) and the sensors read wrong, and the ABS light comes on. Pull the Sensor out, clean the surface, grease it up so it wont happen again (for awhile) and you should be good. This also effects the 4WD as it read the ABS sensors to see if the front tires are "slipping" , the AUTO setting wont work, and in standard 4W High or Low it can make it feel like the one tire is braking when tight turning on non slippery surfaces. Depending in miles (100, 000+ is my guess by price) you may just want to invest in 2 front hubs (they include the sensors most of the time) as they will be well within replacement time.. Check engine light is probably the P0446 (gas tank vent code) which will make ZERO difference on how the truck drives. Never need to fix if you don't mind the light. QUite common on these trucks too. Sometimes that code is even a bad sealing GAS cap. But it could be anything, did you code read it?
The real problems with these trucks, Piston slap on many.. annoying sound, but seen um with 300,000 and piston slapping like a jackhammer when cold. For some reason they seem to plug heater cores, listen to the Dex-cool haters/lovers.. seen it on tucks with it or without it, so no idea.. also easy to combat if you back flush them every 80,000 or so.. hoses are right at top of firewall, wont even lose much anti freeze. Blend doors on heater failing.. also not hard to fix if you can lay on floor for 20 minutes... While I wouldnt say problem, water pumps seem to go at about 120,000, watch the weep hole (again easy, when you check oil take a look).. But the worst, leaky intake gaskets.. I have not had one on mine, but several friends have had it, leak at very back so its hard to catch, heat often dries it so it wont leave a puddle but you will smell slight anti freeze smell under hood.
Me i have had a few, some 5.4 Fords, and 1 dodge.. THIS IS OPINION only, the fords seem to ride slightly better, would take the 5.3 chevy over the other two for POWER anyday, GM has the low end torque the kicks in right away, while the other two need some RPM's. My Fords seemed to have way more RUST on the frame i cant understand this, but they just seem that way (and every dam one has had exhaust manifold leaks when they got over 100,000),.. The dodge, just didn't do it for me.. no real complaints except the interior was more wore out then my other trucks, maybe just beat on more when i got it. AGAIN ALL OPINION this last part.
So did you buy it? and damn this thread is month old..