2008 Ford Taurus misfires/jumps at highspeeds and inclines?

I'm 17 and I just bought a 2008 Ford Taurus from a dealer with about 170,000 miles and no warranty. Everything on the car appears to be fine, I had my uncle, who is a mechanic, look at it before I threw out 7k.

But now a month later I've noticed that at about 50mph-70mph the car kinda feels like it's struggling to go or like it jumps? If I stomp on the gas it stops and when it happens it only spuds for a few seconds. When I put on cruise control it usually helps and doesn't do it as often or as hard. Also when I'm going about 40mph+ up a relatively steep incline it does the same thing. The check engine light is not on and it doesn't effect my MPG.

Does anyone know what might be happening? I would kinda like to get an idea of what's going on before I go and ask my uncle for help or take it to a ford garage.

You grossly overpaid for that car. Retail price (what dealer would ask for but probably not get is about $5k for a FWD SEL model to around $6800 for an AWD Limited with Nav and sunroof. Realistic selling prices would be around $3500-$5200.

But anyway, when was the last time the car had the plugs changed? If it's still on the original plugs that would explain it, also could easily be a bad coil pack/coil. I'm leaning towards a bad coil pack/coil though, as I've seen cars with bad coils run fine when not under load, but when they are under load a miss will become evident, but the CEL won't come on.