Hi S.,
Food issues can be SO trying for a family. Dr.Harvey Karp admits that the two things a parent "needs" to be able to do for their child is Feed them and Comfort them - and when they cannot, it throws everything off. So understandably, this is difficult because it can become a control issue and truth be told, you can't force someone to eat, just like you can't force a kid to poop on the potty.
That said, it does sound like your little one is having definite sensory texture issues. You describe so well what he will and won't eat. He has a preference for crunchy foods (fries, crackers, cereal, toast) but does not like textured foods that he has to chew - could be a texture issue combined with oral motor issues such as decreased oral motor strength/tone making chewing hard.
You definitely want to get it looked at. This is often not something a child will grow out of. The book "The OUt of Sync Child" by Carol Kranowitz is a great book that the library often has. Another one on food issues is "Just One BIte". You could also probably google, sensory food texture issues, and get a whole host of information.
I don't know if there is a Childrens Hospital or Clinic near you but you will want a pediatric therapist who has some experience in eating issues.
Sometimes, it doesn't take much work to turn things around. Esp when the person making the request is not MOM! Just as for a teacher children will do things they won't do for mom. It can be similar with an Occupational Therapist. There may be other sensory related things going on that you are only seeing in the food issues.
Does he have a hard time with change? Transitioning from one thing to the next? Different textured clothing? Have a preference for something and it MUST be that way - like wearing the same pajamas over and over and over because they "feel good".
There is hope and there is help. You are a wise mom to begin to ask questions about what you are observing.