Offroad-Express

I have a 1990 Toyota 4Runner 2.4l petrol and its running on 3 cylinders I have replaced the plugs leads dissy rotor and cap and still running on 3 cylinders any ideas with what it could be?

Pull a lead until you find the cylinder that's out. The idle won't change when you find the dropped cylinder.

Is it a y series or a 22r?

its a 22r engine. so after I do the lead check what do I do after that?

You need to identify what cylinder it's missing on, then I would swap components from that cylinder with a different one and see if you can 'move' the problem. Change the spark plug and try again, if it's still the same cylinder then move the lead and try again, then move injector, and if it's still the same cylinder then might pay to do a compression test.

okay will try these things now

Is it the 22R carby model or 22R-E injected version?

is the carby model.
have checked it is the 2nd cylinder missing plug and lead have proven no problems have changed them out

With the sparkplug out of the cylinder connect it to the lead and lay the plug on the head. Crank the motor over and see if the plug fires. If it does then its on to the next step....

Time to do a compression check then and see why that cylinder isnt firing.

Might have damaged valve train or cylinder/piston

Matt.

Does it sound like its chuffing out the exhaust? They do burn exhaust valves. A compression check will let you know if the fault is in the engine then do a leak down test to identify where it is.
Or just re name it a 3 Runner

did compression check today it is the valve piston or rings. thanks to all that helped with this problem

That's unfortunate mate, sorry to hear but good on you for taking advice and finding the problem easily.