about a month ago i got a CEL for my Cat so being dutiful I changed not ONLY the Cat but also both O2 sen. as the car has 250K on it already
after doing that my car ran fine for a few weeks then threw a code for the EGR system so i replaced the EGR valve and cleaned out the egr plumbing...I figured since the hood is up anyway ill do a lil maint. changed VC gasket plugs wires dizzy cap and rotor....started the car it ran beter than ever...for 10 miles developed a terrible misfire and threw the blinking CEL.....what can cause this...ive checked valve clearance, plugs plug wires and made sure everything was properly gapped and wires where they were supposed to be....im thinking coil but would like some input....thanks in advance

after cleaning egr plumbing and replacing valve that code stayed clear
#1 cyl is firing no doubt....other plugs look box new
misfires until u get to speed then seems to settle down until u hafta accelerate again

 

When was the last time the t-belt was changed? You stated that "started the car it ran beter than ever...for 10 miles developed a terrible misfire and threw the blinking CEL". So I would have to assume the tune up is not the issue, though not out of the question.

Check the timing to be sure the belt didn't jump/slip. If that checks out, check using a timing light to be sure the dist. didn't get "moved".

 

thanks for the reply poorman....will do that as soon as the rain lets up....have a new coil in the trunk too....a tech friend of mine said sometimes a weak coil would show itself after new plugs and wires

 

ok the coil was needed...the tip of the old one was melted short and round....changed it rolled her to TDC and checked the marks and they are dead on...cleared the CEL drove it everything was GREAT! for about 10 miles.....then it started missing again and the CEL started flashing....aaarrrgggghhhhhhh!!!!!

 

UPDATE: pulled codes with a jumpersince someone has borrowed my scan tool without asking!
Got code 8 - TDC int. voltage, no voltage, disconnected
code 23 - knock sensor circuit fault
code 71 - random misfire
code 74 - Cyl. 4 misfire

8 and 23 are BRAND NEW whats up with that BTW i checked the connections to be sure they hadn't gotten disconnected

codes BEFORE the coil swap were 71, 72, 73 & 74