T100 1998 check engine light missing. Went to Advanced Autoused their hand held plug in and cyl # 5 missing with code p305 came up.Took it to Toyoya in May landing,N.J. $407 later they show me acracked plug and clean the throttle body. 175 miles later check engine comes on again I go to Advanced auto same code p305 cyl # 5 missing. If I had the fireing diagram order I would buy one new wire to see if it would solve the problem but i can not find the diagram anywhere. Back it goes to Toyota and they are in for one really pisseed off customer..

You have an interference motor. If you had to replace the heads due to the valves possibly touching the motor, you have to consider rechecking the compression after you replaced the heads. I had the same motor that had an intake leak. I found frozen rings on the number 1 piston as well as a bent pushrod. Ultimately, the camshaft had broken due to coolant getting to the bearings. If the spark is good, the fuel is good, then the only other problem you'd have would be compression.

Check connectors for injectors and plug coils. The read out would have told you what injector or plug was faulty. Come back with the code numbers.

These use seperate coil packs for each cyl. and I think you have a bad coil pack on that cyl

If your question is what do the codes mean, each one is for a miss on the cylinder with the end number. Code 305 is for cyl 5, etc.
Could be ignition or fuel injector related.

It is most likely a defective gas cap seal. They should have recommended this cheap replacement part first.

Check the spark plug wire and spark plug on #8!

Most likely you have a bad COP (Coil On Plug) .
Maybe more than one. Very common ford problem for last 12 years.
If you get a MIL Light on the dash (the wrench),check for a PO300 Code.
A PO304 would be coil #4,PO306 #6 Etc.
Cyl 1 thru 4 on pass side
Cyl 5 thru 8 on driver side,front to back

Also hills cause a hi engine vacuum and thus a possible EGR Valve going bad. You can unplug the vacuum lines and plug, to diagnose that issue.

Also leave the EGR disconnected if your working on coil issues. Just note the MIL light will stay on all the time,and remember to check your 300 codes if you feel a hesitaton or miss.

pull all plugs for compression check /turn engine over fore 5 sec for each cyl,should be 10 lb and no more from one to the other .
tim

i checked the computer. Following error is showing:
1. P115
2. P1300
3. P1565
4. P1349
5. P1656