Rough idle issue

[COM86]

86 Comanche. 2.5 5speed 4x4.

Start up and warmed up,  I have a rough idle. But normal acceleration. 

Replaced 

Fuel filter,  spark plugs and wires, cap and rotor. 

Next will be checking the vacuum system for leaks. 

Would a leaking head gasket be a symptom? 

[eaglescout526]

Head gasket would be present under acceleration as well. Do some sensor checking. 

[gogmorgo]

I'd keep checking for vacuum leaks. The manifold gasket isn't uncommon, the bolts seem to like working themselves loose which can lead to a failed gasket, but check all the lines as well, you're dealing with 33 year old plastic components. 

A leaking head gasket is usually a cause, not a symptom. Typically they present with some very noticeable symptoms, cross contaminated fluids, pressure and bubbles in the cooling system, etc. You could do a compression test if you're really concerned, but I'll point out that I once had a 2.5 with a bad head gasket and hole in a piston, 20psi compression on that cylinder, and it ran and idled fine, just blew out all the contents of the cooling system both onto the ground and into the oil in pretty short order and only started running rough when it had dumped enough coolant to overheat. 

[cruiser54]

Put a wrench or socket on all the intake and exhaust manifold bolts. Likely loosened up.

 

Refresh the grounds per my Tips. 20 minute job.

 

Check the vacuum lines in the photo below.

 

 

[COM86]

What size of vacuum tubing should I ask for?