The '93 2.6 has a MAF (Mass AirFlow) sensor, not a MAP. It's located downstream and integral to the air filter housing, at the driver's front corner of the engine compt. AFAIK the distributor is the only source of rotation signal to the ECM, there are no cam and crankshaft sensors on this engine.
Check your cam timing. You can pull the upper timing cover and check to see if the mark on the cam belt sprocket aligns with the stationary mark when #4 cylinder (not #1) is at TDC, on its compression stroke.
Be aware that the harmonic balancers on these are notorious for slipping (the rubber bond between the inner part and the outer ring breaks) and then the timing mark on the balancer won't line up with TDC. So be suspicious of that if things don't line up right.
If things seem off, there are 2 ways to determine TDC for belt alignment purpose: use a timing stop or dial indicator thru the spark plug hole, or pull the harmonic balancer & lower timing cover, then use the alignment mark on the crankshaft pulley, which lines up with a stationary mark on a cover at the front of the block.
Make sure your firing order is correct, and the dist. rotor is pointing at the correct cylinder to be sparked. You can do this with either #4 or #1 cylinder (both are at the top at the same time). Whatever cylinder you reference off of (1 or 4) must be at TDC compression stroke.
It's not uncommon to see clogged injectors on these, too. You may be able to isolate your problem cylinder(s) by doing ignition or injector "drop" testing. i.e., pull a plug wire and see how much it changes idling. Same idea, disconnect an injector electrical plug and see how it behaves.
If the particular cylinder where you unplug an injector or pull a plug wire doesn't make much difference in idle quality, that cylinder isn't pulling its load and has some sort of issue.
This is an extremely informative thread on cam timing and ign timing adjustments, unfortunately due to the Photobucket fiasco in the past, the pictures are no longer viewable. Still a lot of great info if you can follow along:
https://www.planetisuzoo.com/viewtopic.php?t=60015
BTW, if you haven't adjusted the valves, do so. A couple of tight exhaust valves can mess things up, and these engines are notorious for burning valves when adjustments haven't been tended to. At least yours has good compression!
Last thought, check both the rubber and plastic air intake tubes for leaks. This problem has come up in a few recent threads, folks have found massive air leaks in the hidden areas underneath. That'll really mess up the engine management!!
HTH & let us know what you find..........ed
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