I'm going to try and explain this as best as possible. For about a week now my rpm guage has been "jumping" at about 3700. When i give gas while at 3700 rpm the tach jumps up to about 4200 then holds there for a moment then falls about 300 rpm then jumps back up about 500 rpm, it likes to do this most in 4th and 5th gear but i have had it do it in 3rd as well. However while the rpm tach is jumping u can also hear the fluxuation in the engine but the speed consistantly increases, it's like you can hear the motor get the gas hard first then it bogs or stumbles then recieves the fuel again. This has me stummped, it seems it could be the turbo, fuel pump, injectors,... and i have no cel. Any help is very appreciated.