OBD2 missfire, popping, stalling, running rough and starting issues

[Pidge 0]

Ok, as per the title really ive got a few problems with my 97 OBD2 VR. Ill try to explain them as best i can, however i should note here that they are all intermittent, sometimes being really bad, sometimes not too bad and sometimes no problems at all. Also the bad start up is not always related to the running rough.

Ive had the car on VAGCOM and other than a fault code for my ditched evap system theres nothing coming up.

So far ive replaced the leads, plugs, coilpack, battery, fixed the 2 broken wires on my 4 wire lambda, cleaned the cam sensor and throttle body, tried running with the maf unplugged (made the problem worse!), fixed all vac leaks and checked my relays which are all fine.

Ive removed the PCV breather steup and replaced with a vent to atmosphere catch tank, the evap cannister is gone, the throttle body coolant lines have been bypassed and rerouted appropriately. The car is decatted, has had the suitcase silencer removed, a bmc and power rohr are also fitted.

So first off, the bad starting.

Last year i made/fitted a hockey puck engine mount + spacer as i was having sump clearance issues. The old mount was totally minced so i immediately noticed a difference as the new one is essentially solid, however roundabout the same time the car began to give me trouble when starting. It could take a few goes to start and be fine or sometimes it would go first time and splutter for 3secs or so before picking up a normal idle. I do know that my start switch is gone as the car has a 'start' button fitted descretely under the dash which just supplies a live to the starter motor and works perfectly. I will get round to replacing the switch but for now i dont see it is a major issue.

Now the missfire/popping, running rough and stalling.

The car will intermittently run rough from start up (both cold and hot), my driveway is on a hill so i usually know within a minute of starting whether its going to be a good day or not. The car will feel hesitant until it clears 3k rpm then will suddenly spring into life and be fine until i go for second and so on. Occassionaly this missfire can be really bad and the car will just refuse to pick up the revs.

Ive tried realigning the TB both manually and via vagcom (basic settings) and this doesnt seem to solve the problem. When the car is running rough like this it will sometimes cut out on the slow down for a junction etc or if i dip the clutch the revs will drop right down to around 4-500rpm and hunt for a good idle. If i touch the throttle during this the car will either die or return to a normal 750 idle. Also, when running rough the car feels very hesitant to the point that if i dip the clutch and put the throttle all the way down itll hesitate around 4k and will either backfire before revving right round or will just go fine

When on the move this hesitation can be quite bad. The car will feel as though its not sure if it wants to go or not, will sometimes pop back out the inlet then go or itll just sit and missfire its way up the revs. This problem can also come or go when on the move and has once or twice started missfiring only for the problem to disappear after a few miles!

I did think initially that this could be caused by moisture or damp air (living in scotland we get alot of that) but it can happen in the dry or wet and the car can run perfect in both conditions as well.

Im at my wits/monetary end and dont have a clue what to check next. From searching it seems it could be realted to any number of things but ive not found anyone with exactly the same issues that hasnt resolved the problem by replacing all of the things ive tried.

Oddly when the car isnt running rough like this it flys and makes 190+ hp on the rollers with 128k under her belt. I use the car everyday and with this being so hit or miss im really starting to get pee'd off with it

Any suggestions/advice would be much appreciated!

Oh and sorry about the long winded post.