I recently put a 1985 300td turbo motor, and a 4 speed manual transmission in my 1980 300td. It seems to run ok, but not as fast as I hoped. I live in the mountians and I need to at least keep up with traffic. Intermittently it is VERY slow. I am wondering what the problem is. The vacuum lines for the EGR and the Turbo (California motor) are not connected to anything. I tryed connecting the pressure line from the intake directly to the IP (bypassing any electronic components) and it had no effect. I have found however that if I shut the car off for a few minutes the car runs better again. Any ideas would be helpfull.

Anyone check valve lash or injection timing lately??

No I have not. I will look in to valve lash and inj. timming. Do you think that could cause an intermittent problem? Is ther an electric fuel pump that could be weak or poorly connected?

Normally, the valve lash or IP timing won't cause an intermittent problem.

This would typically point toward a fuel filter. Change the secondary lately?

The engine has a mechanical fuel pump. It's unlikely to be the culprit.

Brian, I wonder if his "intermittent slowness" corresponds to low fuel tank level? Maybe a fuel tank strainer or an air leak someplace.

I changed the primary fuel filter and it looked realy clean. The last slowness episode was fitha full tank of fuel. Any chance it is emisions control system related?

I'd clean the tank strainer.

Also, if the primer pump leaks when you pump it you should replace it.

If it's still got the TrapOx under the turbo, it may be clogged. An Italian Tuneup could cure it.

Do you have any emission controls equipment in place? Is the EGR still installed and functional, maybe it's sticking open, just a guess?

I have done the Italian tune up. No smoke. The EGR is in place but the vac line is not connected. I put a vac pump on it and it made a big difference... it ran really poorly, knocking etc. So it works but it should be 100% closed when there is no vac.?? Primer pump is leak free.

Change the secondary filter. Must do that on principle to rule it out.

Check the valve lash. Same situation.

How about cleaning the banjo bolts?

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Secondary fuel filter is easy. I will have to read up on valve adjustment, in tank filter, and the banjo bolts. Thanks so much for the help.

Ok...

So I replaced both fuel filters, adjusted valve lash (according to my book .004in intake and .014in exaust with engine cold), I measured timing chain stretch (eyeball method... line up the cam marks and read balancer for TDC... Thanks for the DIY tutorial.). It is just under 2 degrees out. I think I have ruled out the tank strainer by reversing the fuel lines under the hood. I have adjusted the ALDA and even experimented with removing the ALDA all together. I even replaced the Air filter. The turbo sounds like it is spinning up ok, and I cleaned out the banjo bolts.

I still lack power and have intermittent SLOWNESS... (like 20 MPH top speed) The slowness seems to happen when I restart the motor warm. If I shut the car off, let it sit for 5 minutes, then restart it, it will be back to its "fast as it ever" but still slow self. It seems to me that inj. timing would be thrown off by timing chain stretch but, my chain seems ok. Is the next course of action to check inj. timing anyway?... Is it comon that inj. timing gets out of adjustment even if the chain is ok? Any Ideas?

Do you have the "old style" primer pump? It's a clear plastic cylinder that will leak fuel everywhere if you unscrew the piston and pump it several times?

The new style is all black and has no piston to unscrew.

It is the new style black one. No noticeable leaks.