Unsolved problem

I have a 1997 jeep gran cherokee 4.0

it takes spells that it will start missing and then quit and will not start but a little later it will start and the code is number 43 also it will backfire and destroy the muffler i have replaced the coil and the crank sensor and muffler of course two times

this is not something that happens with

heat it will do it when it is hot or when it is cold also replaced the engin controle modual or brain.

it may do it often and it may run for monts before it dose it. again always code 43 when it sets a code what is wrong ?

You really need to try to use some capital letters and periods. When you don’t its just really hard for people to follow what you’re trying to say. It would also help if you would give a complete description of your symptoms altogether and then a clear list of things that you have done to try to fix the issues. Include anything that has actually been checked, how it was checked and by whom. (E.g. has anyone checked the fuel pressure?)

You also need to clarify a couple of things. First, if the vehicle is a 1997 then it can’t have an error code of 43. Your system would be OBD-2 and the powertrain error codes will be a P with 4 digits (like “P1234”). Second, it would be helpful to know the vehicle’s mileage and the state of your basic maintenance items, and generally how well you have kept up with scheduled maintenance.

Even regardless of any of that, before I spent another dime I would check the compression.

I read it and had no problems understanding what he said. Roll another n relax

As cigroller said, it can’t have a Code 43. Until that little bit of murkiness is cleared up no one can guess what’s going on.

Backfiring and destruction of the muffler could point to raw fuel being dumped into the exhaust and then being ignited. Maybe engine cranking with no spark and eventually a spark is produced which sets off the entire thing, etc.

As others have stated with a 1997 Grand Cherokee with a 4.0 liter, the code/s will be something like P1234 or p0123. Go to the Zone and have them pull codes for you.

IIRC, Jeeps of this era had a self-diagnostic that displayed codes without an ODBC reader hooked up.
I believe 43 is a misfire code.

You may have a timing chain that’s worn out. If you have a ton of miles, maybe had a bad overheat over the years.
When they’re worn they can jump a tooth, backfire, belch, quit running altogether and than after one or maybe repeated starting attempts fire back up until it happens again.

Peacefrog, that doesn’t surprise me - b/c I’ve struggled through your blurtings as well.