I had many of your problems with my 92 Toy 2WD 5 speed for the past eight years or so.
I went back to NGK plugs, new wires, new cap, new rotor, TONS of Chevron Techron, etc. NOTHING WORKED !!!!!!!!!!!
I had a fairly rough idle, a bog or delay on my 1 to 2 shift and slightly decreased mileage .
Then one day I re-read the Haynes manual and it mentioned something I had never seen on any other vehicle =3D as EGR VACUUM MODULATOR FILTER. It said if you have ROUGH IDLE, SHIFT LAG, AND DECREASED MILEAGE, then clean or replace that filter.
On my car there is a vacuum line going to the EGR valve but AHEAD of the EGR valve and in the line is a MODULATOR.
I took the thing apart after removing the three vacuum lines - a 5 minute job. Unit slips out of a clip.
Inside was a pissy assed little white filter =3D size of a half dollar and about =BC inch think made of white material similar to what you find on some sponges.
I blew it out with air and WOW. To date the idle has improved about 50-75%. No more BOG on my 1 to 2 shift. I am still waiting to see if the mileage improves to where it was - it was down about 4 mpg over normal which on highway was like 27 for a 4 cylinder.
Haynes manual said to BLOW OUT WITH AIR if dirty. It was not really that dirty, but blowing out with air worked for me. I am going to treat "ol' paint" to a new one for whatever it costs.
Hope this helps.