P0300 code keeps flagging. misfire occurs during acceleration to letting off of accelerator pedal at 2500 rpm or higher.

A plugged converter will cause a NO power situation where the vehicle is unable to expell exhaust gasses and cause poor acceleration. A flashing engine light is the result of a misfire. ( spark plug/coil/injector/wiring ). The engine should still be able to accelerate but will have a noticeable hesitation while doing so

sounds like you have checked a lot of things if it was mine I would do new intake gaskets, I had a 2002 Sonoma I did a lot of what you did and every time I gave it back to owner a few days later lite was on and p0300 I did intake gaskets and its been good 2 yrs now,not sure what gaskets you got but gm use plastic ones I got new gm ones and they were aluminum type call gm dealer parts good luck

This sounds like a transmission problem. I would take this into someplace like an Aamco. Have them do a diagnostic for 80 bucks to eliminate that or get it fixed while it is still cheaper to do.

I think you have an engine wiring harness issue going on here.

There are a few conditions that will not set a code. For example, stumbles are often caused by ignition coil problems. If the problem persists at a certain RPM, could be an O2 sensor problem in closed loop operation not lasting long enough to set a code, or a fuel regulator or injector problem. I would get a good code reader and check readings from all sensors in the circuit (including misfires) to see if you can pin down the problem.

p1227 Oldsmobile Injector 2 Control Circuit Shorted
p1245 Oldsmobile Intake Plenum Switchover Valve
p1275 Oldsmobile Accelerator Pedal Positioning (APP) Sensor 1 Circuit p0300 Oldsmobile Multiple Engine Misfire Detected p0172 Oldsmobile Fuel Trim System Rich (Bank 1)
sounds like bad injectors for one and computer needs relearned or replaced unfortuantly u gotta goto to the dealer have diagnostics ran

All fault codes can be checked out at http://www.bluejag.co.uk but here are the results for some of yours. You can ignor P1111. Looks like a faulty plug or coil pack cylinder 2

Fault Code:- P1314 Indicates a Power-train fault


The fault is generally due to a problem in the Ignition or Misfire area


Fault Description: Misfire rate catalyst damage -bank 2 NOTE: This DTC will flag only when accompanied by an individual cylinder misfire DTC: P0300 - P0306

Action of ECM:- ECM Default:- Maximum engine speed reduced


After clearing the DTC, complete the Misfire monitor drive cycle
Check for a reoccurrence of fault DTC.

Possible Fault:- Cylinder compression low Worn camshaft / broken valve spring(s) Fuel delivery pressure (low / high) Fuel injector(s) restricted / leaking Fuel injector(s) continuously open Fuel contamination Fuel injector circuit fault(s) (Injector DTCs also flagged) Spark plug failure / fouled / incorrect gap ECM to ignition coil primary circuit fault (Cylinder misfire detected DTC also flagged) Ignition coil failure
Fault Code:- P1316 Indicates a Power-train fault


The fault is generally due to a problem in the Ignition or Misfire area


Fault Description: Misfire excess emission NOTE: This DTC will flag only when accompanied by an individual cylinder misfire DTC: P0300 - P0306

Action of ECM:- none


After clearing the DTC, complete the Misfire monitor drive cycle
Check for a reoccurrence of fault DTC.

Possible Fault:- Cylinder compression low Worn camshaft / broken valve spring(s) Fuel delivery pressure (low / high) Fuel injector(s) restricted / leaking Fuel injector(s) continuously open Fuel contamination Fuel injector circuit fault(s) (Injector DTCs also flagged) Spark plug failure / fouled / incorrect gap ECM to ignition coil primary circuit fault (Cylinder misfire detected DTC also flagged) Ignition coil failure

Fault Code:-
P0302 Indicates a Power-train fault


The fault is generally due to a problem in the Ignition or Misfire area


Fault Description: Misfire detected ?€" cylinder 2

Action of ECM:- none


After clearing the DTC, complete the Misfire monitor drive cycle
Check for a reoccurrence of fault DTC.

Possible Fault:- Refer to P0300 Possible Causes

P0300 is random engine misfiring. Could be several problems. My car had this and I replaced the plugs and plug wires. No change. Checked the three coil units. They seemed ok. I used a new on in each spot and nothing changed. Ended up being the ignition control module that sits under the coils. Relatively easy to change. Costs around $150 at the parts store. This may correct the other codes.

I found this; if it helps.
The injectors need to be cleaned, if an engine is experiencing any of the classic symptoms of dirty injectors, such as lean misfire, rough idle, hesitation and stumbling on light acceleration, a loss of power, and higher hydrocarbon (HC) and carbon monoxide (CO) emissions.
Lean misfire may also trigger a misfire code and turn on the Check Engine light on 1996 and newer vehicles with OBD II systems. The code often will be a P0300 random misfire code, or you may find one or more misfire codes for individual cylinders, depending on which injectors are most affected.

the web page was:
http://www.aa1car.com/library/2003/ic30336.htm

Hope this helps