No idle after change of head gasket

[einar]

I’ve just replaced the head gasket on my Camry 1989, 3S-FE engine. When the engine is started, it want idle and it is not possible to reasonable adjust the timing. The engine seems to run fine when the RPM is above 1000, however there is excessive light-grey exhaust/smoke. We have checked and re-checked and are COMPLETELY SURE that the camshaft, timing marks, distributor, timing belt etc. are correct assembled toward each other!

However, we might have done a blunder when the head was taken off the engine block: We were not aware of the lifters covering the valves and all of these fell off at an inattentive moment and hence they were all mixed. In the Haynes manual (read afterwards) it is noted that these should not be mixed!

So to my questions:
Any ideas why the engine does not idle?
Are the mixed lifters the (obvious?) reason?
If so (i.e. mixed lifters), is there any way to sort out the problem?

Any advices would be highly appreciated as we have run out of ideas!

[Doctor J]

I would start with leak-down test to make sure that valves are closing completely;
The light gray smoke at 1000 RPM indicates high crankcase pressure