Fuel Injector Replacement?

Good day, and thank you in advance for looking at this!

I just purchased a 2001 Tacoma 4x4, 2.7L 5 speed - I forgot how much fun it is driving stick! 145K miles on it. When I purchased the truck, the previous owner was very upfront and stated that there was a problem that had cropped up after he posted the ad for it. The previous owner had a garage look at it, and they suspected a bad fuel injector. As he had already posted the ad for the truck, he knocked an additional $500 off the purchase price. I then hooked up a code reader, and found 7 error codes. They are:
P1315 Toyota - Igniter Circuit Malfunction No. 4
P1310 Toyota - Igniter Circuit Malfunction No. 3
P1305 Toyota - Igniter Circuit Malfunction No. 2
P1300 Toyota - Igniter Circuit Malfunction No. 1
P0401 Toyota - Exhaust Gas Recirculation Flow Insufficient Detected
P0303 Toyota - Cylinder 3 Misfire Detected
P0300 Toyota - Random Cylinder Misfire Condition

The truck shakes a bit on cold startup, and seems to level out after it warms up. It drives great, but I'd rather get this fixed sooner rather than later.

Two questions: do the codes listed above seem like a fuel injector problem, or should I be looking at something else?
Second question - I'm relatively good at car repair. I can change my own oil, brakes, rotors, etc., and have never attempted to do something like swap out injectors. Is this something that a weekend warrior such as myself could do? I've got the Haynes manual and all the tools I need.

Any advice/opinions are much appreciated!

 

i think you should be looking at the igniter…. a bad one can cause random misfires, and heres 4 codes for it. A tube for the egr valve could be plugged up, thats something to check also