1993 Allante, no light or relevant codes, roughness with very occasional miss at idle which improves with injection cleaner (Techtron or Liquid Molly) and goes away completely after hi-speed highway trip of 250 miles or so but then comes back after some days of city driving. However, there is also a stutter/judder at 2000rpm in 4th on slight acceleration and on a slight rise (going up an overpass). (Has had tuneup plugs/wires/coils to fix hard miss w/ trans code & codes a year ago). Car runs strong on hard acceleration. I'm stumped and don't just want to throw injectors at it. What is this I hear about replacing trans solenoids?