My 1993 940 Turbo has lost it's power. Timing is right-- 10 degrees BTDC and properly advances when accelerated, brand new knock sensor is properly torqued and not too tight, brand new RPM sensor, butterfly throat cleaned, new plugs and good spark tubro works well but there is just no power. The transmission shifts down with the slightest new load and even then the acceleration is poor. I have a brand new CAT and muffler with the correct size pipes.

I have run out of ideas---it feels like the timing is being retarded but when I check it with my light, it's good and does advance.

Any suggestions/solutions?

I had similar issues with my 1993 940T. It took me a long time to discover that the wastegate actuation arm was sieized to the actuating piston. After I whacked the connection many many times and the over use of PB blaster over several hours it loosened. I pulled the rod off the actuator arm dowel and cleaned and lubed with silicone greased and replace; now works very well. The problem for me now is to remove those parts of the small pin that have remained on the waste actuator dowel.

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1993 940T wagon

Ditto here: the cotter pin stuck in the hole. I ended up using a Dremel flex extension shaft with a narrow drill bit, drilling out the hole. I recall it was a real pain. I replaced the cotter pin with stainless.
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See the 700/900 "FAQ" at the menu bar top screen left side.

Besides removing and inspecting the induction hoses as already suggested, check the wastegate actuator arm and make sure it is still connected.
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john

Check the rubber hoses that go to and from the intercooler. They deteriorate over time. Take then off to thoroughly inspect them and you will probably find a hole or tear in the bottom of one of the hoses.

Jimo