One problem related to steering idler arm has been reported for the 1998 Ford F-150. The most recently reported issues are listed below.
Left tie rod on my 1998 Ford f150 broke while driving. I bought truck new in 1999. Mileage on truck was 29900. Had truck towed to dealer, they informed me that right tie rod needed to be replaced too along with the lower ball joints and idler arm. I was on the highway just 20 minutes before. I was lucky. Service manager told me he has needed to replace them after 15000. From the factory there are no grease fitting for lubrication. Also none on replacements. Please call or e-mail with any questions, thank you.