22r misfiring

I have a 90 hilux with a 22r engine. It misfires if I drive it cold and leave the clutch out going down a hill. Once warmed it doesn't misfire. A friend suggested I adjust the timing, and I did, but still the same problem. The friend said that since the timing chain has some slack in it , I might try to adjust the timing beyond the factory recommendation 0 tdc. Would appreciate greatly any comments from people who've had the same problem with their 22r.

I'd look at the choke heater operation.

First check your plugs and wires and make sure there good, clean them if need be. Does it use oil? Maybe it just needs a good cleaning. If your timing is ok when warm then leave it be. (My suggestion, my 89 22r has the same issue but it goes away in about 2 minutes after it warms up.)