88 4x4 2.3 FI
starts fine, idle is a bit high 1200+ when driving, often will seem to loose power, sputters, not pop or backfire, at any speed, hit the clutch an gas peddle and seems to straighten up...briefly and repete .
unable to determine if electrical " ignition" or fuel delivery related.
new fuel filter, new TPS, new ign module, cap, rotor, ign coil, new fuel pres reg, MPG is miserable, no initial vac leaks detected.
really need help with this one.
what are the chances injectors plugged up ??

 

Seafoam(or similar) in the gas tank once a year will keep fuel injector tips clean.

But no that wouldn't be the problem, dirty injectors don't get better.

Pull out a few spark plugs and look at the tips, very light brown means engine is running with good air/fuel mix, darker brown or blackish means running rich.
If plugs are dark then that's the drop in MPG, if they look good then you have a leak in fuel system somewhere, or a neighbor with a siphon hose, lol.


High idle is normal cold, and after warm up when coasting above 5mph.
But after warm up and stopped idle should be down around 800rpm for 2.3l, automatic trans vehicles idle higher than manual trans.
After engine is warmed up unplug the IAC valve, rpms should drop to 500 or engine may even stall, either is good it means no vacuum leaks, if idle stays high then you have a vacuum leak, or someone messed with the anti-dieseling screw thinking it was an idle screw.

Next would be to check fuel pressure at idle then at steady 2,500rpm for a 2 minutes see if it is dropping.