1999 crown vic miss

ok so I have been having a issue with my lx model vic blowing out a coil every month even though they are all new along with the plugs and boots as of 6/13.I just had one blow the other day and the code I pulled was cylinder 5 misfire so I changed that coil and still feels like its missing and wondering if anyone has any ideas of the problem ,also I have had issues with my evp sensor and also changed that after reading it can throw a false code for bank 1 cat being out and also I was hearing a ping out of my pass exsuast which I read was do to a faulty evp sensor ,I had changed it back 6/13 and it was ok for about a month then it actted up again where it didn't have full power so I changed it again 3 months ago with no change in how its running so I can't figure out what may be causing these problem but my car has a bad bog if I am light on the gas if I floor it it moves almost like normal also the only thing that isn't stock is my duel exsuast which came off of a 02 p71 that has the h pipe with no mufflers would this cause any issue because I had no issues at firt when I hooked them up any info would be helpful

If you changed exhaust, you would have to make sure you have the same (correct) O2 sensors installed. That could be a problem...Dave