Question1999 ford ranger 4.0 engine. new wires, plugs,mas,throttle control valve,idle control valve,have cleaned throttle body. engine misses under load, then smooths out. foot off gas it shutters real bad then smooths out again. engine has 115 K miles.seems to happen mostly between 45 and 55 mph.plugs are gapped at 054.
AnswerIs the check engine light not on? If not, change the fuel filter id you have not already done so. The lack of the check engine light may point to a fuel problem. Test the fuel pressure at all stages,idle, 1500 rpm,2000 rpm, 3500 rpm, and finally at 4000 rpm for a short period of time. Of course, that is only if the fuel filter is not the problem. If the light is on, have the codes read for free at most of your local parts stores. Don't delete them, the light will go away after the problem, if mechanical, is fixed. The only other sensor you have not listed, that may cause your condition would be the EGR valve and or solenoid. Get the codes read, even if the light is not on.
