I was having a terrible hesitation and idle would be sometimes at 200 other times 800 and surging. Found Throttle Position Sensor was bad and got used one on ebay for $18. No almost all the hesitation is gone but at idle, which is around 800, it's moving up and down constantly. Say from 750-850.
I have checked for vacuum leaks, cleaned the Idle Valve Control Valve which was a bit gummed up. Also cleaned the EGR valve. New spark plugs, rotor and cap along with air filter. It's now mostly ok but wife drives this so would like it to be as good as it could be. Its 4 cylinder with 219,000

 

good work so far

if fuel consumption is bad will need more investigation

not on your list
have plug leads and coil been changed or inspected
in the dark ,bonnet up,run the motor look for arcing

specs from 93 repair manual

4 cyl idle spec is 750 + - 50 ( with cooling fan off)
i assume bit higher idle with air con on and for an automatic

4 cyl timed at 10 degs



if no better
valves are shim clearance
Intake:
N = T + (A – 0.24 mm (0.009 in.))
Exhaust:
N = T + (A – 0.33 mm (0.013 In.))


if still uneven an engine compression test see if there is a leaky valve

 

Gas mileage has gone done but not sure how much. Wife won't keep track of fuel as I told her to do so don't have a good idea of how much. Haven't checked the plug wires yet, but will. I'll check these other things you mentioned. I hurt my back and can't do anything for a while. Aside from the problems i mentioned the motor is very strong once it gets going.

 

Today when starting rpms were about 800 with some fluctuation and almost no hesitation when accelerating. Go up to Walmart 2 miles and after 15 minutes inside car now has terrible hesitation when trying to accelerate. I stop and park. Rev the motor which revs fine except very bad shudder. Rev it 3 or 4 times and drive off. Now hesitation is gone. I'm just going to observe how it does every day, since it seems to be changing all the time.

 

revving the motor gets better

wonder if it is the fuel filter or bad fuel or fuel pump or relay

when you are able check the bits as mentioned

 

All the things I found out of spec and replaced did not solve the problem. I did check the coil and it checked out. But after reading several posts about how coil had been problem for a lot of people I got one off ebay. I used to work in motor dept building motors for circular saws. I remembered how the varnish holds the magnet wire in place and if it goes bad it will let wires vibrate and rub the insulation off. Thinking about this I got the coil. Its been in for a week and problem is gone. No more fluctuation with idle, no hesitation. No low idle. Only problem is small drain on battery which i temp solved by taking fuse out till i find out what is on that circuit. Wife has been pestering me to take it in to shop for weeks now but I refused. She admitted she didn't think I'd ever figure it out.

 

better to be a DIY er
money saved can buy flowers ,a dinner out or chocolates for wife

oh sorry I cant help you on the battery drain fault