Hello everyone.

I've found a few posts discussing some similar issues but I don't think it is answering my question.

History:
A few months ago the check engine light came on and lost all power, assumed limp mode. Scan tool at the mecahnics said basically it was the airflow sensor, I got another (unfortunately not OEM) and everything was fine for a while. Then recently I started experiencing overboost and when driving through gears I'd normally always hit limp mode at about 2-2500 rpm in 3rd/4th gear (same at 110kmph), give the throttle a blip then all good. Then the engine light has started coming on recently and only a few minutes after starting the car and would stay on. I purchased a MAF from repco (hitachi brand) and the car doesn't seem to hit limp mode... but the engine light keeps coming on. Got out my Haynes manual and bridged pins 1 & 8 on the plug to clear the code. This worked, but the very next time i drove the car... engine light. So again with bridging the pins, when i did this i got the code 1003 (ten flashes then 3). when i googled for some info i found that code 1003 is: EGR volume Control Valve circuit malfunction, EGR volume control valve failure.

so currently while accelating through gears: i don't seem to get limp mode. Watching the boost gauge it hits 20psi and holds til gear changes or sometimes it hits 20 and 'bounces' until i get to cruising speed.

Has anyone experienced this before? any suggestions?
Ask a silly question. will an overdue oil change cause grief? oil that is too thin or something?

The car:
- 2001 ST 3.0L.
- Has dawes/needle valve and EGR plate. (boost set to aroun 17psi, needle valve pretty much has vnt wide open)
- A safari Dtronic chip has been fitted (i think i got that correct).
- The exhaust is 3" (no idea on EGTs)
- catch can is fitted (pre-issues)
- from what i can see, all boost lines, hoses and connections are OK

Previously not had any issues like this since buying the car.

hopefully i have covered everything