So a couple weeks ago I got a code P0304; miss fire on cyl #4. When the CEL came on it felt like the motor fell out of the truck, but only for a second. it was ok afterthat, but over the next couple weeks the power feels like it's been dropping off with no more codes, or otherwise any other problem other than it felt like I had a v6 instead of a v8. It runs smooth, andidles smooth, just feels like lost power.

Before I throw ignition parts on it, anything specific I should look at? no loose wiresor anything.

It's a stock 318, other than the flowmaster exhaust. Gas mileage is the same also.

 

When's the last time the air filter's paper element was replaced?
Because, if the truck can't breathe...

 

I thought because i occassionally go off roading (light trails) that that could be an issue, but the airfilter is ok. not new but ok. I also looked down the throttle body for tell tale signs of a bad intake gasket, but there was only a very light film of oil, so that's ok too.

 

Still got the stock cat in there?

 

affirmative. but it passed the 'tap' test; no rattling.

 

just because it does not rattle doesnot mean its not bad see if its getting really hot and the pipe after is cool

 

i agree with TPSDODGE. when my cat clogged it didnt rattle. i had the same symptoms as you except i had a cylinder 8 missfire

 

pull your cyl. 4 plug and see if its still good..

 

Yep. Mine was hitting with about 10lbs(?) of back pressure. After I had it replaced, the difference was night and day. A clogged cat will throw a misfire. I completely rebuilt my engine and got a sick feeling when the CEL kept flashing and I pulled the misfire code (yet again). Took it to a muffler shop and they did a backpressure check, which confirmed the cat was clogged.

 

so yep, looks like it is the converter. Problem is I'm getting over bronchitis now, so it'll be a few more days still until I get around to it.