backfiring and heavy hesitation.

Got off the highway, car died. Started but had to keep rev up to keep running so I got back onto the highway to go back home. Ran for 30 minutes at 75 mph (1900 rpm) but would hesitate when under load and "pop". Sounds like I'm running only 6 or 7 cylinders. Check ompresssion (145-150 all the way around) replaced plugs with Autolite 25 gaped .052-.056 and cap, rotor and FMS 9mm plugs. Still barely drivable with popping and same heavy hesitation. I am going to replace the TPI module tonight. How to I test if the injectors are working as seems to be my next hunch. I still really sound like I'm still running on 6 or 7 cylinders. The car ran flawless before including 300+ miles this weekend. Any help is great!!

89 LX Convert. 5.0 5-speed

Thank in advance

I wil be running the KOER and KOEO test tonight. About a month ago I bought an OEM rotor with 30K miles including FMS 9mm wires and never got around to installing it. I didn't replace the actual dizzy, but swapped the cap/rotor/wires and I am picking up the $4 7/32" socket to replace the TFI tonight was well. I was very relieved that the compression check came out so good at 145-150psi all the way around as the engine has 150K on it. I'll keep everyone updated on my progress.