Sluggish when cold / High speed missfire

[Forester430]

I'd really appreciate any possible help on this.

I have a '95 Corolla, 1.8L, with 150,000 miles. It seems to start and run fine at idle but is sluggish and jerky when taking off at first when the engine is cold (outside air temp has no effect). Once warmed up it seems to run fine, except that maybe once every 2-3 miles (worse under a load, uphill, etc...) at highway speeds it will missfire or something. It jerks pretty hard but just for an instant. Replaced plugs, wires, distributer cap, rotor. Seems to be 90% better but not cured. Still doing the same things just not as bad or as often. That part doesn't make sense to me. Any suggestions?

Thanks!

[ghost_ryder35]

check timing, and coolant level (could have a headgasket leak leaking into a cylinder, antifreeze doesnt explode causing a misfire).

[hishamzz]

check fuel injectors.. might be clogged and warm temperature usually thins the clog a bit but then when more fuel is required.. it might not be able to supply.. just might be your prob..

Zz