4.0 OHV rough starts and vibrating idle

[Nonstopmaximum]

I have a headscratcher problem my 94 Ranger starts fine with first drive of the day but if I'm away for about 15-30 minutes and try starting it again it will struggle to start unless I give it gas or keep key turned for a few seconds. It vibrates every 2-3 seconds with idle at 600-700 RPM in drive or reverse, slightly less in park. Replaced IAC and that made idle vibration way less severe, MAF cleaning did nothing, no vacuum leaks, everything fuel related except injectors themselves have been replaced. Injectors are my prime suspect right now but I think I'll try spark plug and/or coil pack replacement first. I'd like to hear what everybody thinks before I continue there.

 

[franklin2]

Replacing the IAC improved it, did you also clean out around the throttle body and the IAC passages? All that brown gummy stuff?

 

[SenorNoob]

So warm restarts are a problem? If so, I'd suspect cracked head or bad gasket. The coolant in a cylinder causes a misfire only after it's been up to temp and started to cool down.

 

[Nonstopmaximum]

Got rid as much grime in the throttle body I can get I noticed there's a lot inside the upper intake manifold. No cracked heads boroscoped them and they're good and not losing coolant. Putting Seafoam in the tank has sometimes gotten rid of the rough starts for a few days but they come back.