1995 Saturn SL2 Rough idle, varying RPM's, pressure in valv

First of all thank u so much for ur donation it really helps to keep this site going and answering everyones questions.I would check and make sure the plug wires are in the correct order on the coil side it goes from left to right cyl 4 1 2 3 and on the engine side number one cyl is on the passenger side and they go 2 3 4 working to the driver side.I would also check the pcv hose for a vaccuum leak. Also get a can of carb spray let the engine idle and spray every where there could be a leak if the rpms go up or down or the car stumbles or dies when ur spraying u have a leak there. Also take out the pcv turn it upside down with the valve opening that goes into the valve cover facing straight up if it is not completely closed tight replace it means it has a bad spring. Let me know what u find.

Ok lets do this since u have a obd1 system and most auto parts stores can only read obd2 for codes heres what I want u to do. On the drivers side bottom of the dash theres the obd1 connector where u would put a code reader on. Look at the row of it far right side theres two pins side by side. Turn the key to the run postion dont start it and jump those two pins together and leave it that way. Watch the service engine soon light flash.U will see it flash once then two faster flashes. Thats a code 12 that means the computer is good it will do this 3 times if it repeats the code 12 after the 3 times u dont have any codes. But watch the light for example if u see 3 quick flashes then 2 quick ones that would be a code 32 it would repeat 3 times then go to the next code when it gets back to code 12 then the codes are done. Let me know what codes if any u have then we will check out egrs and all that. Talk to u soon.

So u just have a code 12?So the car ran fine before u changed the valve cover?Those egr valves on that model get carboned up and stick causing high idle missing dieing. Try this take off the egr valve turn it over look at the pintle it's spring loaded take a pocket screw driver push the pintle down slowly all the way to the bottom slowly release it if it sticks open or is sticky pushing it open at first u have a problem. Let me know what u find.

ok so u only had a code 12 when u flashed the codes out?no other ones?like if u checked now u might have some other ones.sounds like its running differnly now?i wouldnt have changed ur throttle postion sensor they hardly ever go bad.whats been throwing me off is u said it ran good before u changed the valve cover gasket.sounds like this might have been happening before maybe it got worse?i posted a diagram of where ur coolant temp sensor is its the bottom one in the diagram and on the head.it could be causing ur problem there like 10 easy to change.a bad one will cause erratic idle dieing surging overheating all kinds of things and its pretty common for them to go bad.make sure the engine is cold u will lose coolant.make sure u inspect its connector if its corroded u will need to replace the connector.also make sure u get a brass tipped one the plastic tipped ones crack and leak into the connector.thats ur best bet right now.let me know what u find.