Can my truck be saved?

I have an '02 Chevy Silverado basic model. About six months ago it started having trouble starting and by that I mean it would only start after we towed it from our home to the mechanic. There the 1st mechanic said it was our alarm system that was stopping the truck from working properly so that was removed and the wiring redone. That did not solve the problem. The 2nd mechanic after 2 and a half weeks of working on it said it was the thermostat chip reading engine temp incorrectly so that was replaced. We have also replaced the fuel filter and the spark plugs. Couple of odd things about this situation, it works every time we have it towed somewhere so its a couple of days of sitting around before the mechanic can see the problem, the spark plugs were sheared in about a month so we’ve had to replace them twice in the last six months. The truck’s systems do not trigger any of the tests that either mechanic ran & now it is having trouble when it first starts up of just running in general, it has to ‘warm up’ so to speak before it runs normally. Anyone have this happen to them?? Anyone have any ideas what’s wrong??

Paragraphs, paragraphs, paragraphs, please. Your post is extremely difficult to read, and this substantially reduces the likelihood that anyone will answer.

Was the alarm system original equipment or an aftermarket unit?

What does “the spark plugs were sheared in about a month” mean?

Sorry! This is my first time ever posting on the net. I will keep that in mind for future thanks!

The alarm was aftermarket put it in by its previous owner.

The mechanic said that the spark plugs had been flooded with gas b/c the thermostat was miscalculating the temp and then when we would let the engine crank for a few minutes to get it started that it sheared the spark plugs so that they were no good