99 996 CEL issue

[R996]

I started my car up yesterday as I was checking my starting issue and a flashing CEL came on. I shut my car off as I know a flashing CEL is bad. The codes that came up were 

0300

0301

0302

0303

The car didn't run any different if these codes were there or after I cleared them. Is there any chance there is something wrong with my computer as I've had other codes in past P1531 & P1340. I have had it to 2 different mechanics and there is nothing wrong with my timing as it was checked. I did however last year have a misfire and it did make the car run rough. I had all the plugs and coils changed and of course the misfire went away. I'm just asking why I get all of these codes, sometimes 10 different codes,  Sometimes it's P0301 and sometimes it's P1319 , same code. I don't want to start throwing parts at the car as it runs fine, idles fine. It's just a little frustrating when the CEL comes on. 

[DBJoe996]

P0300 is a generic code for misfires.  P0301-P0303 are misfires for cylinders 1, 2, and 3. Your other post is about hard starting.  I would start by checking the fuel pressure at the fuel rails.  There is a valve just for that purpose.  Also, at the same time test fuel pressure bleed down.  That will test your fuel pressure regulator.  The Bank 1 misfires may be either electrical (coils/plugs) or fuel.  When was the last time you ran some fuel injector treatment/Cleaner (like Techron) through the system? Also, actually remove the engine ground wire and clean up the connections from any corrosion/rust.

[R996]

 Thanks for the info about the fuel test. I did change all the coils/plugs last year, that's why I'm having a hard time trying to figure out why the misfire codes are coming up as the car runs perfect. As I said, when it did misfire last year,  before I changed coils/plugs, it worked terrible and would hardly stay running. I did read in another post about low fuel level causing misfires. I do run Seafoam a couple times a year but I have never fun a fuel injector cleaner.

Do you mean the ground strap behind the pass side wheel? I haven't done that in a couple years actually. I did do it trying to figure out out my "hot start" issue. I'll see when I can get my car into my mechanic so he can do the  fuel pressure check.