Toyota Repair: 98 4Runner Hesitation on acceleration, vacuum problem, spark plug wire

Question
I have a 98 4Runner SR5, 4 wheel drive, 3.4 V6 automatic with 192,000 miles on it; purchased at about 130,000 miles.  Lately, it hesitates and bucks slightly between about 58 and 64 mph - both in OD and not.  Just changed the spark plugs, fuel filter, air filter, oil and filter.  Trans fluid is good at both hot and cold levels.  Put 2 new coils and 1 new injector in 2 years ago.  The injector was bad on cylinder # 3.  Recently it coded #2 cylinder misfire (before the tune up).  Put some injector cleaner in and cleared the code and it hasn't coded since.  Could this be a coil/spark plug wire problem, or vacuum problem?  Regular shifting seems to be smooth and uninterrupted.  Idle speed is okay and very smooth.  Have the ability to do all electrical/resistance or current checks.  Thanks for any advice.

Answer
It wouldn't be a coil problem since each coil fire two cylinders so if the coil was bad it would give a misfire code for two cylinders, in this case the #2 cylinder is paired with cylinder #5 so #5 should also show a misfire, it's very possible that another injector has gone out, this is why it's recommended to replace all of them when one goes out, injectors are not cheap so unless you want to relace them all try replacing the #2 at this time and see what happens.