I recently replaced the seals, gaskets timing belt on 1988 Toyota
Camry. After running it for a few weeks it started missing real bad -
barely got it home. A friend determined it was the distributor/coil
and this was replaced. The other evening I checked the timing,
although timing was OK I did not get a consistant firing from the
number 1 cylinder spark plug led (timing light emmision was not consistant)
- seemed to misfire. I drove the car
around the block and again barely got it home and into the driveway.
Before turning engine off the RPM's were up around 2500 (at idel)
although earlier it was 750 rpm. After a few seconds the rpm's settled
back down but did not remain even - jumping between 750 and 1000 rmp.
Also noticed a knocking a the lower end of the engine - but only when
warmed up. Vehicle has about 290,000km. Any ideas?

 

I'm sure you've checked this, but are you absolutely sure that the crankshaft and camshaft are lined up to their respective timing marks? Did one turn with respect to the other while the belt was off?

I had an old BMW 318i with over 325k miles that began to act the way your Camry acts. I replaced the coil, rebuilt the distributor and adjusted the timing -- all to no avail. Although I never definitively identified the problem, I believe that the timing chain in the car had jumped a cog.

Since the distributor is driven by the camshaft, the ignition timing will be off if the timing belt is on incorrectly. The knocking that you hear could be engine damage due to interference -- again due to a possible timing belt installation problem. I'm a shade-tree DIY mechanic and not a pro, so I can only offer you a suggestion from my own experience. Good luck on finding the problem and a solution -- I hope that it is something simple.