I''ve got a 1991 trooper and in 5th gear on the freeway (60mph)under heavy load it will backfire. It drives fine under all other situations. Any ideas for this would help.





Thanks

 

Hey, for the backfiring, check your plugs to make sure that none of them are cracked. After that, check your plug wires. It could be a bad plug wire. Last but not least, check your timing, if the timing is off, it can do that as well. Hope this helps