1987 4.9l F-150 will start up good cold and run well. The problems are usually on restarts hot. It will begin to surge up to about 1200 or so, then drop so low it will stall if it doesn't recover. Sometimes I will also smell oil burning when this is happening but it isn't a significant amount - just enough to smell. Reving doesn't help, just drive it a few miles and usually the problem is gone. (It's a four speed, by the way so this makes it a handful to try to get out of a parking lot!) I have: Replaced cap, rotor, plugs, and ECC. No improvement noted, but all that work definitely needed done anyway. It has a fresh oil change and clean air filter. Thx!

 

I probably should have gone with my first instincts and replaced the fuel injectors first. I replaced (in addition to the things mentioned in the OP) fuel pressure sensor, 2 vehicle speed sensors, throttle position sensor, and throttle control solenoid. After all those parts it still had the same surging problem. I checked fuel pressure at the fuel rail and it was fine - so, not pump related. Then I replaced the injectors and that did the trick. I didn't even buy "good" injectors, but a set of imports that were about $12 each. When the AC is on the idle is still a little irradic and it will stall occasionally, but I don't need to worry about that for about 6 months. I haven't run it enough to check the fuel mileage but it seems better and I'll report when I have that info. It still smells a little rich at idle - not sure if I can do anything about that. I considered removing the air pump and EGR crap, but I think that would have just been a lot more work so I left it alone. I was a little tickled to see Ford's solution to vapor lock (I assume) with the added air blower that directs a stream of cooling air at 5 of the 6 injectors....Really? I had the fan unplugged because it ran one day for about 45 minutes after I shut the engine off. I've got it hooked back up now and so far so good. I'm still having some weird intermittent electrical issues (like the air blower thing) but, the truck is over 30 years old, so I guess that's to be expected. I read a lot of posts on here about similar surging and stalling issues but never saw anyone pinpoint it to the fuel injectors, but that's what worked for me! I think the injectors (maybe just one, who knows) were drooling instead of spraying - so, at idle, fuel was being dumped into the engine, the engine would rev, and the engine controls (which were probably working correctly) would attempt to reduce the RPMs and it would sometimes stall. Add the AC throttle control problem into the mix and you had what I had. I notice now, that the RPMs drop more gradually back to idle instead of dropping almost instantly - I think that helps with controlling the idle speed.