I have searched this site many times to try and find an answer to my problem but I cant find anything specific enough. With that being said, PLEASE HELP ME lol.
I am experiencing a loss in power in 2nd and 3rd gear (in my 1997 AUDI A4 1.8T QUATTRO), If I am accelerating at a constant rate I get a flat spot (feels like I have let off the gas) between 2000 - 3000 rpm then the power kicks back in. Most of the time I get the flat spot during acceleration in 2nd gear at about 2750rpm and kicks back in just after 3000rpm. The strange part of this problem is that I have never had it happen in 1st, 4th or 5th gear and I have never had it happen outside 2000-3000rpm. The problem does not constantly happen either, It can happen 10/10 times or I may drive for 2hrs and it not happen once. It does not seem to make a difference if the car is warm or cold, if im going around a corner or not, up a hill or down a hill, driving hard or easy.
The clutch is new so it is not an issue of slipping, the turbo was checked and seems fine, the air filter is new, the spark plugs are new, there are no errors being read by a scan tool so it is not a misfire, it has happened for awhile so it is not bad gas or anything, I have slightly low voltage so I had a new alternator put in (fixed the voltage but not the flat spot) so i put my old one back in.
Im not sure what else it may be, any help would be greatly appreciated. Thanks alot everyone!

 

Now might be a good time to invest in a boost gauge to see if the probllem is in the turbo control circuit which i suspect it is. Sounds like a valve thats sticking somewhere in the control circuit. Either the n75(wastegate control), diverter valve, or the diverter valve control solenoid. Could also be a maf, fuel pump, or filter proplem but considering its more load dependant i would start with the turbo system.

 

Im doing the fuel filter in a couple of days because I need to do it anyway, but i would say that your probably right about the turbo system (but you never know). Whats a maf? and where can i get a good boost guage with a 'middle of the road' price tag?
Thanks alot for the reply dankhound.

 

Maf is the mass airflow sensor. It is located on the airbox and sends a signal as to how much air is entering the engine. As for the boost gauge, just about anything will work as long as it reads to about 15psi of pressure. I know of a vacuum/fuel pressure gauge that is sold at sears that will fit the bill for under 50 bucks but you could probably get something off the internet for cheaper.