Forester steering issue

[Raspberryroulade]

I have a 2004 forester XT which I think has developed a steering issue, but unable to find out what it is.

When driving on single track roads the car is extremely twitchy. I am constantly having to alter the steering to stay in a straight line, the same happens on motorways in the first lane on sections that are particularly rutted from wagons. I've had the car in to the local garage but tracking and track rod ends are all okay. I've had the car for six years and up until a couple of months ago the steering was spot on, the mileage is just under 140k.

Any ideas?

Many thanks

[Marshffs]

Are your balls joint quiet? Same happened in my wrx and was the bottom ball joints. Excessive play. 

[Mr B]

Ball joint and wishbone (corrosion issue, has a recall) and  wishbone bushes need good looking at .

Check steering rack bushes too .

can you feel any play in steering when stationary and rock steering wheel left to right .

[Raspberryroulade]

Sorry for the delayed response. All have been inspected and all are in good condition. One possibility has been mentioned. A friend had a similar problem with a Kia Sorento fitted with Michelin tyres. Never occurred to me it could be my tyres, she had Vredestein fitted before the Michelins that I put on about a year ago. Could this be a possibility?