Hello again. I have a Subaru Turbo 2000 - 1999 Reg. Had some great advice on here before so back for some more....

So I come to my next problem....I've noticed that when I go into 3rd, 4th or 5th and give it the beans it seems to hesitate through the rev range (dull patches), it doesn't seem like the clutch is slipping as it's only gradual and clutch feels fine. I was thinking that maybe it's getting the wrong fuel mixture or there's too much air getting into the mixture?? It has a K&N filter and dump valve so was wondering whether they could be the culprits and need a change of filter? Anybody else had these problems?

Boost leak from dump valve or leads/plugs need a change

And 95ron fuel will give problems.

as said by gambit the problem is most likely going to be the wrong fuel or as mat said a DV sticking, does your dv make a whossing sound or is it quieter than before, try testing all pipes to make sure none have perished with age, and check the top mount inter cooler if it still has one, as these are known for the odd stray stone causing some issues.

Thanks guys, the replies are much appreciated.

Ever since I purchased the car a few months ago I've put the best petrol in, Ultimate BP or Shell V-Power. Should I try the normal petrol? (Another quick question after watching 5th Gear, they added Redex to help clean the engine on an old car - good idea or bad idea for the Subaru engine?)

I will have a look at the dump valve, it makes a whooshing noise but not very loud. When I bought the car the guy said it used to be a lot louder, so it could be this. I will report back.

Won't be the fuel then and I always recommend a bit of redex through too just helps keep things a bit cleaner. I'd just check you have no leaks or loose jubilee clips too letting in more air. when under load. 

I had this problem, is it hesitant at low revs but fine after that?

 

I had a cone filter on, I changed it back to the standard air box and seems to be fine now.

 

Although martin at sheffield subaru service said same as above about the dv, I wouldn't say mine runs 100% at the minute after returning back to stock filter so I will check dv soon too 

it could be the maf as in the late classics they were not very good and cone filters tend to kill them as I know to my cost

I had similar issue and turned out to be the spark plugs. Worth checking

From what I have seen all of the above are culprits for it :( 

it's a case of narrowing them down I'm afraid.

im going to change my maf on pay day as i think it is  on its way out

I always have a spare

best way to test is unplug it and start the car without it