so i recently got my car to work as some people would know, i now have the issue with the number 4 cylinder again, it starts and runs off 3 cylinders but after about 2o minutes of rough idle ,the engine has heated up, the number 4 cylinder starts to fire and run normal, with smooth idle

is there any reason as to why no4 wont fire on cold start??? i have changed the plugs and leads. . . .

I knew someone that had similar problem with a sigma.. after $$$$$ it was a cracked sleeve

Cracked sleeve can be found with compression test and leakdown test. Have you done either?

Most common cause of problem like this is a vacuum leak on #4 intake runner.

Whatever,you do, test before replacing more parts. Save yourself time and money.

when i had it citric dipped, the mechanic done all that for me, i have not done either since, is the sleeve replaceable if this is the problem?? how do i find a vacuum leak??

Look carefully at your inlet manifold near the #4 runner. Are there missing fittings cracked hoses or a hissing sound?

Check your valve adjustment. It's possible that the clearances on you # 4 cylinder are too tight, causing one or both valves to be slightly open until it warms up.

not that i know of? there is a squeaking sound but im sure thats the exhaust not hooked up properly i will do a compression test soon, how do i do a leak down test? i will be sure to go over everything associated to #4

Check out that squeaking sound. Put a lenght of hose to your ear, and move the hose over the engine until you pinpoint it.

ok will do, i done the compression test and all 4 come up at 149/150 , so cant be a sleeve can it?