Engine running lean

Bought this car from a friend. I've had it for around 6 months now. It had sat for approximately 2 years unused prior to purchase. It started right up, and we've drove several tanks of gas through it since then (with Seafoam of course). It has simultaneously gotten worse and better as time went on. We've put on a Master Brake Cylinder and an EGR Valve. Replaced and replenished all the fluids, and now I've sent it off to have the spark plugs changed and the valve covers replaced. That's just a bit of background info to keep in mind.

The day that I took the car to the mechanic it started to drive the worst it ever had before. Before the symptoms worsened we had stopped to get 100% fuel from a local garage. I had noticed before that it would run a little harder after getting gas before this, but didn't think much of it at the time. Anyway, once we got the fuel we attempted to crank it and it wouldn't turn over. It took several attempts before it would fire up. Once we got back on the road it started missing and losing power more and more. Long story short we barely made it to the mechanic's garage.

Symptoms: loss of power (especially when pulling uphill), misfiring, occasionally it would rev up whilst accelerating, rough idle, and a whining sound that sounded to be coming from the motor area when accelerating. All of these symptoms worsen as the vehicle heats up. When I would raise the hood the heat from it would be hot enough to burn you if you touched anything metal. Sometimes there would be smoke coming out when I would pull out the oil stick. However it has never once ran hot on the gauge. Sometimes the fan will kick in for long periods of time even after shutting it off. Kind of worried and baffled me at the same time. Why would the fan run that hard if it's not overheating?

I've hooked an OBDII to it and the last time it read as follows: Lean on bank 1 and 2, Misfire on cylinder 6, random misfire, and a large leak in Evap system.

My theories were leaning towards catalytic converter, ignition coil packs, and/or fuel pump. The mechanic I took it to called and told me that he believes the entire throttle body is bad and that the Ignition coil packs could be playing a part as well. Before I throw any more money at parts for this thing I'd like to get some outside perspectives on the matter beforehand.

Any and all thoughts are appreciated! Thank you in advance.