miss and a backfire through the air box
 

94 e150 4.9. when i accelrate to take off i have a miss with a back fire going through the air box. i bought the van with this problem i drive it twice a week to deliver my sunday papers. pass smog with that miss too. it does have a miss once the van is almopst warmed up kinda like when i take off but it doesnt back fire through the air box. has anyone have this issue? thanks

Mileage ?
What kind of routine maintenance has been done ?
Plugs, wires, coil etc?

i bought this van with a bad steering gear box and had the clutch fan replaced. it looks like it has a fresh tune up by looking at the wires and distribruter cap. i have 256k and still doesnt use a drop of oil. motor really clean for this mileage.

Something we learn and sometimes the hard way, Don't take anything for granted check the plugs for gap etc. also the timing. Just because they look new has fooled many a careless tech. Check everything, then you know where you stand. Look for vacuum leaks or cracked vacuum hoses. Backfire in the intake is usually caused by a lean condition.

i just hope its not a bad valve.