1) Alternator
2) Timing belt slipped
3) Turn signals went out
4) engine runs hot
5) paint peeling off
6) passenger side window sticks
7) transmission problems
8) car misses
9) Red seats faded to pink/orange
10) car vibrates/ shakes when driven
11) door panels have come loose
12) passenger side door handle exterior and interior need replacing.
This car runs so badly its good for nothing, I've kept this car up just like the owners manual says and it still has fallen apart. I never knew Ford was so cheap-
This year was known for faultiness. There were a number of lemons. I have a friend that recently hung up his '90 Mustang due too many similar problems you've got listed. It's always a shame finding yourself with a lemon and being scarred from a potentially good product forever.
I have an 89 LX convertible with the same anemic 2.3 liter turd. I haven't had any of the problems you have mentioned except the costly one. The A4LD 4 spd automatic transmission. This is a truly crappy transmission from the Ford Motor Company. Mine died at exactly 103,000 miles. I also had to put a front seal in it at 68,000. The one in my dad's 92 Ranger blew seals at 98,000. The 2.3 liter is a great engine. My brother's 88 LX had 256,000 miles on it when he sold it and it had never been opened up. His was in front of a 5 spd manual. (The only way to go if you buy the 4 cylinder.) As far as I'm concerned. Steer clear of the A4LD. Ford's AOD and Borg-Warner T-5 found in the 5.0 liter cars are much better.
I also have a 1990 Mustang and it has almost all of the same problems right down to the ugly red interior fading.