Engine loses power drastically, wants to bog out?

I carelessly bought my truck listed above pick-up 'as-is', which has numerous issues. The 5.7 V8 has well over 200,000. It starts up strong and right away upon turning the ignition key, which I thought would be an excellent 1st impression of the truck. It turns out I was mistaken. So, it starts right up then it idles okay, with to me sounds like the usual noise of older engine lifters clicking; upon acceleration, it loses power drastically, wants to bog out, and the auto transmission feels like it 'slips' into action while it has that acceleration issue. After an embarrassingly long 15 - 20 seconds, the truck catches its breath and drives as well as to be expected with an over 200,000-mile work truck that feels and looks like it has not been maintained accordingly. This is just the 1st question I will be presenting to you, so I must thank you in advance for your knowledge and assistance.