sounds like you have a case of the maintenance! My m50 needed the following to bring it back to proper health, similar issues.
New O2 (obd1)
removal of maf, and cleaning ! brake cleaning fluid, fully dry
intake boot checked for cracks and cleaned
vacuum lines replaced
icv cleaned
new spark plugs
Throttlebody cleaned spotless
intake mani cleaned out 100% no more grime
Results, rock steady idle @ 560-600rpm, no stuttering, no jittering, starts up super easy in minus 10+
Costs: peanuts