ok. VDO is better in fuel economy is better than MMC. But MMC is easier to mess with. VDO is self adapting so imho it's easier to play with but quite difficult to mess with.
Because VDO is self adapting it uses a lot of sensors vs the MMC. These sensors are all wear and tear so it's worth checking them out and replacing them. O2 x 1, MAP, crank, cam sensors swap them all out. Ignition coil, ignition cables swap them out. TB is a question mark because if it's not broken, don't touch it. The mechanism inside the TB is bloody sensitive. Knock it a bit whilst cleaning then you'll need to get the PDT scanner to reset and clear the fault code. If you don't clear the code the car will run really rough. Also a car this old better have a look at the brake lines, if got budget swap to steel braided ones. I recommend Supercircuit ones.
You want better FC get a PNP head, skim the head down and use the Wira SE header or an aftermarket header. Then use a 2" exhaust system throughout with a quiet rear muffler. Throw in a resonator if it's still too loud. Forget about s-flow or twister exhausts, straight good old fashioned exhaust is better even for autos. Use lightweight 15" rims and if you want to upgrade the brakes the GSR ones are PNP. You can get a lot of extras like Satria GTI rear arms to have the ARB link brackets on the arms itself so can use dogbone type ARB. Also the Satria GTI power steering rack is faster if you're looking for better steering feel. Also a front strut tower bar will improve driving feel. If you still want more can go for UR side bars and fender bars to complete the set. The front ARB just use the GSR one.
Satria GTI seats or Putra seats are PNP too and are way better than stock seats. Oh if you can find one, the Satria GTI R3 is the best Satria out there and it's road legal seam welded from factory. Rare but the best. Else get a Wira C99 car. Avoid the 1.3 at all costs.
Good luck with your search.
