Hi, Ive had the car for year and a half and am gradually getting it back on the road. Was misstreated and sat under a tree for a long time but dont know much more about its history.
Has had an intermittent miss since I got it, despite taking it to the local jag mechanic who fixed abs warning light, front headlight, and he was supposed to get it running smooth. They changed three coils, and supposed to be running smooth but not so. So I changed the other coils, with hitachi ones and put ngk plugs in. No change starts first time runs smooth enough then an intermittent hiccup starts ..... followed by shaking on and off once she gets warmed up.
What could be the issue here...fuel pressure? Dirty fuel filter? Oxygen sensor? Broken wire causing intermittent short? Thermostat not opening? Injectors? Any thought on where to start what to look at would be appreciated

 

Well, I can throw a few guesses around, but it would be better, if you'd connect an OBDII reader and let this thing tell you what the issue seems to be...

Yes, fuel filter is a good guess, maybe start with this. A (partially) blocked fuel filter will probably not be recogised by the OBDII reader...
Oxygen sensor is also an option, but there are 4 of them.
What about your fuel? Is it old fuel? Any fuel older than 3 month could possibly cause issues...
When I bought my V8 3.2L it was barely driving and was in restricted mode. The OBDII reader told me what it was: It needed a new Knock-sensor. Easy fix.

 

Looks similar to what I have. on my car happens as car goes above 4 k rpm, it starts shaking as if there was a fuel starvation.

There is so much to look at. Plug an OBD, look for errors and monitor some love variables: fuel trims, throttle position.

 

That too is something to check, yes: Check the connectors to the throttle position sensor AND the connector to the throttle position motor.
The latter connector is prone to damage by the heat in the engine compartment in X-Type and S-Type, maybe on the X308 as well...
Thus, if a damaged connector causes some intermittent contact, this might cause all kinds of unexpected issues.

 

Fuel filter; temperature sensor in the cross-over pipe (stuck, it continues a 'cold' start signal to the ECU through the MAF, causing it to run too rich); dirty throttle plate and bore; dirty MAF sensor; dirty air filter.

 

I've just fixed a lumpy idle - previous owner had renewed the O2 sensors, fuel injector rails and various other parts along the fuel system.
2 minutes with a can of easy start around the induction path located a rather large unmetered air leak....

If you have an OBD reader that can give you live data, you need to check your fuel trims, short term both banks. If it's a negative percentage by a lot, it's usually an unmetered air leak and the ECU has conflicting reports from MAF to O2 sensors.

 

Hello, I have some vibrations at idle. When you say lumpy idle, it means fluctuating rpms?

 

Yes

 

Thanks gents ill look into a few of those and report back. I might start with unmetered air, then the fuel filter because they sound easiest!!!

 

Replaced fuel filter....with difficulty I might add, and seems to be running better. The old filter was FULL of rust. And I suspect the tank at some stage has had water in it, the question is has it stuffed the injectors? May get them cleaned anyway.

 

Congrats.

Did you ever measured fuel pressure?