I have a 1986 Ranger 2.9L V6 Automatic that has died a few times on me but otherwise seems relatively fine.

When I first got the truck the idle was about 800-900 in park. I decided to install a coil kill switch for theft prevention and immediately started having high idle +1200 at normal temp. I kept the switch and within a few days the truck died in the driveway after a 30 minute drive, 10 of which was in a drive thru idling in gear, no issues, as soon I hit the driveway it died. It wouldn't start, after 2-3 tries I gave up. After 2 hours I decided to take out the kill switch to trouble shoot it and the truck started. I reinstalled the switch and the truck still started. Ultimately I took the kill switch out, but still had high idle.

For the next few days it still had high idle but did not die. I treated it with Lucas fuel treatment, up to 25 gallon treatment in about 15-18 gallons of fuel. On my way home from a 3 mile trip it died 3 times, once while moving down the road. Each time it started after about 5 minutes. It has not died since, it's been 4 days. Since then, the idle while in gear stays around 1000.

I'm not sure but I think it may have a misfire, but never cuts out under acceleration, but will once in awhile when coming to a stop. The reason I think it may have a misfire is because I can hear what I call a "puh" in the exhaust? every few seconds.

Other symptoms are, sometimes it has a rough start, I would say it's much easier to start cold, but always starts within 2-3 seconds, usually 1-2 seconds. It blows white smoke from the exhaust when cold but goes away after 5 minutes or less, it ticks on cold startup for about 15-45 seconds.

It shows zero signs of overheating, but I do smell antifreeze a little, so I changed the radiator cap, jury still out on the smell. I opened the radiator cap to look for bubbles in the coolant, no bubbles, it appeared to be circulating. When I changed the oil it looked used/old and not milky.

It may have an oil leak, but this has not been verified. It's possible the power steering is leaking and blowing back on the engine. When I changed the oil I sprayed the bottom of the oil pan and transmission pan because I saw a red drop on the bottom of the oil pan. I have never seen a drop on the ground and do not see any accumulating on the bottom of the oil pan since then, about 2 weeks ago. It also appears that the grease and grime on the underside of the engine has a red tinge to it and the power steering pumps looks pretty wet. However I have not cleaned it, so I'm unable at this time to give more info.

It gets horrible gas mileage, which I wasn't expecting great, but it seems to be around 8mpg, mostly driven at 35-45mph and mostly under 2500rpms when accelerating. It has good power from what I can tell, 70mph easily up a 1400' mountain pass with a decent grade.

All in all, I'm worried it's a head gasket, but thinking it's the fuel injectors, fuel pump or fuel filter.

Tomorrow I'm doing the chemical head gasket test, the one that changes colors and cleaning the throttle body. I would like to clean the fuel injectors by removing them or doing one of those pressurized cleaning kits, but idk if it's worth it or if I should try new injectors.

We really like the truck. The body has 69xxx miles and the engine has 12xxxx miles. We're considering getting the engine rebuilt, but not sure if there is a better option or even how much something like that costs.

If anyone can point me in the right direction on any of these issues, thank you.