Need help
 

I have a 99 Impreza turbo and I've been having issues my wallet and I can't seem to beat car started hunting at idle and anything over 3.5k rpm and the car starts spitting and popping and all power cuts in and out as it spits and pops went to a garage who said good news not head gasket bad news O2 sensor after being parted with 150 squid hunting stopped but other problems continue I'm going to replace TPS Incase this is to blame fuel filter changed and fuel system cleaned. If anyone has experienced this and knows what to do please help me

Standard car?
If not, what mods and is it mapped for them?

What you describe could also be MAF related, you could replace the MAF?

P{S: if it is, stay off boost until it's sorted, or risk it going bang.

Not mapped only has air cone and vent to atmosphere dump valve MAF is only two weeks old I thought the same thing so replaced it. The car boosts fine till 3.5k rpm then it starts like it's blowing but can't find source boost pressure has dropped from average high of 10psi to 8psi but still seems to pull like a train till high Rev

So it's had the intake changed and a VTA dumpvalve fitted?

It needs the map checked asap, let's hope you get away with it. You can't mess with the fuelling on these cars and hope it will be OK, they don't like it. And the cone filter is, effectively, messing with the fuelling.

If it were mine, the standard recirc d/v would go back on too. ;) There is nowt to be gained and much to lose from a VTA one:(

I bought the car as it is a year ago and the old owner had the car 4 years and never touched a thing either so I only think it's not been mapped but I guess if it's run that long with them without problems then it must have been mapped noticed a lot of vids on YouTube of people with the same hesitation bucking problems under load it's all pointing towards TPS just seen how much that are £150 for a spring in a bit of plastic any other make car £25 another middle finger to scooby owners from parts company's