surging and stalling

i have a 92 xlt 4.0 and have a problem with it surging and stalling i just got a tune up and that did not help the iac wash "cleaned" andd that didnt really help much either i drove it yesterdayafter gettingit back and drove 1 1/2 iles away to the auto parts to buy fuelsystem cleaner and on my way back after it had warmed up it started surging and if i didn keep a foot on the gas while stopped at stop sign it will stall. i was about 5 block s from home and the check engine light came on . my friend brought over his scanner and it passed the 2 four letter ( cant remember what they were but they only change by like 1 letter) checkes then it displayed code 172 . i was able to drive it home i started just fine and after it had sat before i went home the engine light went off. my friend has never worked on fords before so he seems to be clueless on this. all my problems started after it had sat for 6 months because the rack and pinion had to be replaced. after it wa fixed it strted this and the gas milage went from 12 mpg to 2mpg so i parked it for the last year . now i want it to be fixed so any suggestions would be most appreciated.

My 94 is doing the same type of thing and I was told the EGR valve needs replacing. Getting that done next week. Something for you to look into.

Very carefully check for vacuum leaks, intake leaks, or PVC leaks. Sometimes a rubber elbow can get very soft and suck shut on you.

Hello lucy J Code 172 indicates a lean fuel condition. Have it checked for vacuum leaks this could very likely be the cause. the egr valve can cause the same symptoms as a vacuum leak to. the vacuum hose on an aerostar are subjected to a lot of heat which causes them to deteriorate and crack. Goodluck!!!!!

you can check all you want buy its unlikely you will find the leak on a 4lt. its tight in there. If you look with great difficulty from the rear of the Eng. on the passenger side you will see a vary small vac. line its black hard PVC running up the side of the intake it has an elbow way way up there near the front of the block that comes loose from the rubber connector. Its a small diameter about 1/8 but runs the length of the block. this could vary well be the culprit its a one hand job that requires Patience. but i would first check the 4 vac lines at the rear of the driver side. sometimes the Aerostar has a slight backfire during start up. this has enough pressure to pop the line from the warren elbow also vary diff to reach but it can be unless you have arms the size of ??? Good luc and have a drink before you start. you ll need it .

I just put my aerostar in the shop. They replace wires and plugs. also change out the fuel filter. Also had a vacum leak on the boot that comes from the pvc valve. It had the same systems as your car.